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Page 1 1 FINAL JEE –MAIN EXAMINATION – JULY, 2022 (Held On Tuesday 26 th July, 2022) TIME : 3 : 00 PM to 6 : 00 PM PHYSICS TEST PAPER WITH SOLUTION SECTION-A 1. Two projectiles are thrown with same initial velocity making an angle of 45° and 30° with the horizontal respectively. The ratio of their respective ranges will be (A) 1: 2 (B) 2 :1 (C) 2: 3 (D) 3 :2 Official Ans. by NTA (C) Sol. Let projection speed is u 22 12 u S i n( 9 0 º ) u s i n ( 6 0 º ) R ;R gg ?? 1 2 R 2 R 3 ? 2. In a Vernier Calipers. 10 divisions of Vernier scale is equal to the 9 divisions of main scale. When both jaws of Vernier calipers touch each other, the zero of the Vernier scale is shifted to the left of zero of the main scale and 4 th Vernier scale division exactly coincides with the main scale reading. One main scale division is equal to 1 mm. While measuring diameter of a spherical body, the body is held between two jaws. It is now observed that zero of the Vernier scale lies between 30 and 31 divisions of main scale reading and 6 th Vernier scale division exactly. coincides with the main scale reading. The diameter of the spherical body will be : (A) 3.02 cm (B) 3.06 cm (C) 3.10 cm (D) 3.20 cm Official Ans. by NTA (C) Sol. 1 M.S.D = 1mm 9 M.S.D = 10 V.S.D 1 V.S.D = 0.9 M.S.D = 0.9 mm L.C of vernier caliper = 1–0.9 = 0.1 mm = 0.01 cm zero error =–(10–4)×0.1mm = – 0.6 mm Reading = M.S.R + V.S.R – Zero error = 3cm + 6 × 0.01 – [–0.06] = 3 + 0.06 + 0.06 = 3.12 cm Nearest given answer in the options is 3.10 3. A ball of mass 0.15 kg hits the wall with its initial speed of 12 ms -1 and bounces back without changing its initial speed. If the force applied by the wall on the ball during the contact is 100 N. calculate the time duration of the contact of ball with the wall. (A) 0.018 s (B) 0.036 s (C) 0.009 s (D) 0.072 s Official Ans. by NTA (B) Sol. ? ? i ˆ P 0.15 12 i ?? ? ? f ˆ P 0.15 12 i ? ? ? P 3.6 kg m / s ? ? ? 3.6 = F ? t 3.6 = 100 ? t ? t = 0.036 sec 4. A body of mass 8 kg and another of mass 2 kg are moving with equal kinetic energy. The ratio of their respective momenta will be : (A) 1:1 (B) 2:1 (C) 1:4 (D) 4:1 Official Ans. by NTA (B) Sol. K.E = 2 P 2m ? ? 2 1 1 P K 28 ? ; ? ? 2 2 2 P K 22 ? K 1 = K 2 So, 4P 2 2 = P 1 2 1 2 P 2 P ? 5. Two uniformly charged spherical conductors A and B of radii 5 mm and 10 mm are separated by a distance of 2 cm. If the spheres are connected by a conducting wire, then in equilibrium condition, the ratio of the magnitudes of the electric fields at the surface of the sphere A and B will be : (A) 1 : 2 (B) 2 : 1 (C) 1 : 1 (D) 1 : 4 Official Ans. by NTA (B) Page 2 1 FINAL JEE –MAIN EXAMINATION – JULY, 2022 (Held On Tuesday 26 th July, 2022) TIME : 3 : 00 PM to 6 : 00 PM PHYSICS TEST PAPER WITH SOLUTION SECTION-A 1. Two projectiles are thrown with same initial velocity making an angle of 45° and 30° with the horizontal respectively. The ratio of their respective ranges will be (A) 1: 2 (B) 2 :1 (C) 2: 3 (D) 3 :2 Official Ans. by NTA (C) Sol. Let projection speed is u 22 12 u S i n( 9 0 º ) u s i n ( 6 0 º ) R ;R gg ?? 1 2 R 2 R 3 ? 2. In a Vernier Calipers. 10 divisions of Vernier scale is equal to the 9 divisions of main scale. When both jaws of Vernier calipers touch each other, the zero of the Vernier scale is shifted to the left of zero of the main scale and 4 th Vernier scale division exactly coincides with the main scale reading. One main scale division is equal to 1 mm. While measuring diameter of a spherical body, the body is held between two jaws. It is now observed that zero of the Vernier scale lies between 30 and 31 divisions of main scale reading and 6 th Vernier scale division exactly. coincides with the main scale reading. The diameter of the spherical body will be : (A) 3.02 cm (B) 3.06 cm (C) 3.10 cm (D) 3.20 cm Official Ans. by NTA (C) Sol. 1 M.S.D = 1mm 9 M.S.D = 10 V.S.D 1 V.S.D = 0.9 M.S.D = 0.9 mm L.C of vernier caliper = 1–0.9 = 0.1 mm = 0.01 cm zero error =–(10–4)×0.1mm = – 0.6 mm Reading = M.S.R + V.S.R – Zero error = 3cm + 6 × 0.01 – [–0.06] = 3 + 0.06 + 0.06 = 3.12 cm Nearest given answer in the options is 3.10 3. A ball of mass 0.15 kg hits the wall with its initial speed of 12 ms -1 and bounces back without changing its initial speed. If the force applied by the wall on the ball during the contact is 100 N. calculate the time duration of the contact of ball with the wall. (A) 0.018 s (B) 0.036 s (C) 0.009 s (D) 0.072 s Official Ans. by NTA (B) Sol. ? ? i ˆ P 0.15 12 i ?? ? ? f ˆ P 0.15 12 i ? ? ? P 3.6 kg m / s ? ? ? 3.6 = F ? t 3.6 = 100 ? t ? t = 0.036 sec 4. A body of mass 8 kg and another of mass 2 kg are moving with equal kinetic energy. The ratio of their respective momenta will be : (A) 1:1 (B) 2:1 (C) 1:4 (D) 4:1 Official Ans. by NTA (B) Sol. K.E = 2 P 2m ? ? 2 1 1 P K 28 ? ; ? ? 2 2 2 P K 22 ? K 1 = K 2 So, 4P 2 2 = P 1 2 1 2 P 2 P ? 5. Two uniformly charged spherical conductors A and B of radii 5 mm and 10 mm are separated by a distance of 2 cm. If the spheres are connected by a conducting wire, then in equilibrium condition, the ratio of the magnitudes of the electric fields at the surface of the sphere A and B will be : (A) 1 : 2 (B) 2 : 1 (C) 1 : 1 (D) 1 : 4 Official Ans. by NTA (B) 2 Sol. V A = V B AB AB KQ KQ RR ? AA BB QR 1 Q R 2 ?? AB AB22 AB KQ KQ E ;E RR ?? 2 A A B B 2 B B A A E Q R R 2 E Q R R 1 ? ? ? ? 6. The oscillating magnetic field in a plane electromagnetic wave is given by B y = 5 × l0 -6 sin l000 ? (5x - 4 × 10 8 t)T. The amplitude of electric field will be : (A) 15 × 10 2 Vm –1 (B) 5 × 10 –6 Vm –1 (C) 16 × 10 12 Vm –1 (D) 4 × 10 2 Vm –1 Official Ans. by NTA (D) Sol. B 0 =5×10 –6 v = Speed of wave = 8 7 4 10 8 10 5 ? ?? w v k ?? ?? ?? ?? E 0 = vB 0 = 40×10 1 = 4 × 10 2 V/m 7. Light travels in two media M 1 and M 2 with speeds 1.5 × 10 8 ms –1 and 2.0 × 10 8 ms –1 respectively. The critical angle between them is: (A) 1 3 tan 7 ? ?? ?? ?? (B) 1 2 tan 3 ? ?? ?? ?? (C) 1 3 cos 4 ? ?? ?? ?? (D) 1 2 sin 3 ? ?? ?? ?? Official Ans. by NTA (A) Sol. c v n ? n d sin i c = n r sin90º sin i c = d r dr v n nv ? sin i c 8 8 1.5 10 1.5 2 10 2 ? ?? ? c 3 sin i 4 ? tan i c = 22 33 7 43 ? ? i c = 1 3 tan 7 ? ?? ?? ?? 8. A body is projected vertically upwards from the surface of earth with a velocity equal to one third of escape velocity. The maximum height attained by the body will be: (Take radius of earth = 6400 km and g=10 ms –2 ) (A) 800 km (B) 1600 km (C) 2133 km (D) 4800 km Official Ans. by NTA (A) Sol. e 2Gm v R ? 2 e V GMm 1 GMm m R 2 9 R h ? ? ? ? ? 2 e V GM GM R h R 18 ?? ? GM GM GM R h R 9R ?? ? GM 8GM R h 9R ? ? 18 R h 9R ? ? 9R = 8R + 8h R 6400 h 800km 88 ? ? ? 9. The maximum and minimum voltage of an amplitude modulated signal are 60 V and 20 V respectively. The percentage modulation index will be : (A) 0.5% (B) 50% (C) 2% (D) 30% Official Ans. by NTA (B) Page 3 1 FINAL JEE –MAIN EXAMINATION – JULY, 2022 (Held On Tuesday 26 th July, 2022) TIME : 3 : 00 PM to 6 : 00 PM PHYSICS TEST PAPER WITH SOLUTION SECTION-A 1. Two projectiles are thrown with same initial velocity making an angle of 45° and 30° with the horizontal respectively. The ratio of their respective ranges will be (A) 1: 2 (B) 2 :1 (C) 2: 3 (D) 3 :2 Official Ans. by NTA (C) Sol. Let projection speed is u 22 12 u S i n( 9 0 º ) u s i n ( 6 0 º ) R ;R gg ?? 1 2 R 2 R 3 ? 2. In a Vernier Calipers. 10 divisions of Vernier scale is equal to the 9 divisions of main scale. When both jaws of Vernier calipers touch each other, the zero of the Vernier scale is shifted to the left of zero of the main scale and 4 th Vernier scale division exactly coincides with the main scale reading. One main scale division is equal to 1 mm. While measuring diameter of a spherical body, the body is held between two jaws. It is now observed that zero of the Vernier scale lies between 30 and 31 divisions of main scale reading and 6 th Vernier scale division exactly. coincides with the main scale reading. The diameter of the spherical body will be : (A) 3.02 cm (B) 3.06 cm (C) 3.10 cm (D) 3.20 cm Official Ans. by NTA (C) Sol. 1 M.S.D = 1mm 9 M.S.D = 10 V.S.D 1 V.S.D = 0.9 M.S.D = 0.9 mm L.C of vernier caliper = 1–0.9 = 0.1 mm = 0.01 cm zero error =–(10–4)×0.1mm = – 0.6 mm Reading = M.S.R + V.S.R – Zero error = 3cm + 6 × 0.01 – [–0.06] = 3 + 0.06 + 0.06 = 3.12 cm Nearest given answer in the options is 3.10 3. A ball of mass 0.15 kg hits the wall with its initial speed of 12 ms -1 and bounces back without changing its initial speed. If the force applied by the wall on the ball during the contact is 100 N. calculate the time duration of the contact of ball with the wall. (A) 0.018 s (B) 0.036 s (C) 0.009 s (D) 0.072 s Official Ans. by NTA (B) Sol. ? ? i ˆ P 0.15 12 i ?? ? ? f ˆ P 0.15 12 i ? ? ? P 3.6 kg m / s ? ? ? 3.6 = F ? t 3.6 = 100 ? t ? t = 0.036 sec 4. A body of mass 8 kg and another of mass 2 kg are moving with equal kinetic energy. The ratio of their respective momenta will be : (A) 1:1 (B) 2:1 (C) 1:4 (D) 4:1 Official Ans. by NTA (B) Sol. K.E = 2 P 2m ? ? 2 1 1 P K 28 ? ; ? ? 2 2 2 P K 22 ? K 1 = K 2 So, 4P 2 2 = P 1 2 1 2 P 2 P ? 5. Two uniformly charged spherical conductors A and B of radii 5 mm and 10 mm are separated by a distance of 2 cm. If the spheres are connected by a conducting wire, then in equilibrium condition, the ratio of the magnitudes of the electric fields at the surface of the sphere A and B will be : (A) 1 : 2 (B) 2 : 1 (C) 1 : 1 (D) 1 : 4 Official Ans. by NTA (B) 2 Sol. V A = V B AB AB KQ KQ RR ? AA BB QR 1 Q R 2 ?? AB AB22 AB KQ KQ E ;E RR ?? 2 A A B B 2 B B A A E Q R R 2 E Q R R 1 ? ? ? ? 6. The oscillating magnetic field in a plane electromagnetic wave is given by B y = 5 × l0 -6 sin l000 ? (5x - 4 × 10 8 t)T. The amplitude of electric field will be : (A) 15 × 10 2 Vm –1 (B) 5 × 10 –6 Vm –1 (C) 16 × 10 12 Vm –1 (D) 4 × 10 2 Vm –1 Official Ans. by NTA (D) Sol. B 0 =5×10 –6 v = Speed of wave = 8 7 4 10 8 10 5 ? ?? w v k ?? ?? ?? ?? E 0 = vB 0 = 40×10 1 = 4 × 10 2 V/m 7. Light travels in two media M 1 and M 2 with speeds 1.5 × 10 8 ms –1 and 2.0 × 10 8 ms –1 respectively. The critical angle between them is: (A) 1 3 tan 7 ? ?? ?? ?? (B) 1 2 tan 3 ? ?? ?? ?? (C) 1 3 cos 4 ? ?? ?? ?? (D) 1 2 sin 3 ? ?? ?? ?? Official Ans. by NTA (A) Sol. c v n ? n d sin i c = n r sin90º sin i c = d r dr v n nv ? sin i c 8 8 1.5 10 1.5 2 10 2 ? ?? ? c 3 sin i 4 ? tan i c = 22 33 7 43 ? ? i c = 1 3 tan 7 ? ?? ?? ?? 8. A body is projected vertically upwards from the surface of earth with a velocity equal to one third of escape velocity. The maximum height attained by the body will be: (Take radius of earth = 6400 km and g=10 ms –2 ) (A) 800 km (B) 1600 km (C) 2133 km (D) 4800 km Official Ans. by NTA (A) Sol. e 2Gm v R ? 2 e V GMm 1 GMm m R 2 9 R h ? ? ? ? ? 2 e V GM GM R h R 18 ?? ? GM GM GM R h R 9R ?? ? GM 8GM R h 9R ? ? 18 R h 9R ? ? 9R = 8R + 8h R 6400 h 800km 88 ? ? ? 9. The maximum and minimum voltage of an amplitude modulated signal are 60 V and 20 V respectively. The percentage modulation index will be : (A) 0.5% (B) 50% (C) 2% (D) 30% Official Ans. by NTA (B) 3 Sol. V max = 60 V min = 20 % modulation = max min max min VV 60 20 40 100 100 100 V V 60 20 80 ?? ? ? ? ? ? ? ?? ?? ? ? ? ? ?? ? ? ? ? ?? ? 50% 10. A nucleus of mass M at rest splits into two parts having masses M' 3 and ? ? 2M' M' M 3 ? . The ratio of de Broglie wavelength of two parts will be : (A) 1 : 2 (B) 2 : 1 (C) 1 : 1 (D) 2 : 3 Official Ans. by NTA (C) Sol. 12 PP ? Here P is momentum So h P ?? Hence both will have same de broglie wavelength. 11. An ice cube of dimensions 60 cm × 50 cm × 20 cm is placed in an insulation box of wall thickness 1 cm. The box keeping the ice cube at 0°C of temperature is brought to a room of temperature 40°C. The rate of melting of ice is approximately: (Latent heat of fusion of ice is 3.4 × 10 5 J kg –1 and thermal conducting of insulation wall is 0.05 Wm –1 ºC –1 ) (A) 61×10 –1 kg s –1 (B) 61×10 –5 kg s –1 (C) 208 kg s –1 (D) 30×10 –5 kg s –1 Official Ans. by NTA (B) Sol. dQ KA T dt ? ? A = 2 (0.6 × 0.5 + 0.5 × 0.2 + 0.2 × 0.6) = 2(0.3 + 0.1 + 0.12) = 2(0.4 + 0.12) = 2(0.52) = 1.04 m 2 R th = 22 1 10 10 KA 0.05 1.04 0.052 ?? ? ?? ? 2 2 th dQ T 40 0.052 2.08 10 J / s dt R 10 ? ?? ? ? ? ? 2.08 × 10 2 = m × 3.4 × 10 5 m = 3 3 2.08 0.61 10 3.4 10 ? ?? ? kg/s = 61 × 10 –5 Kg/s 12. A gas has n degrees of freedom. The ratio of specific heat of gas at constant volume to the specific heat of gas at constant pressure will be : (A) n n2 ? (B) n2 n ? (C) n 2n 2 ? (D) n n2 ? Official Ans. by NTA (A) Sol. v nR C 2 ? ? ? p n 2 R C 2 ? ? v p C n C n 2 ? ? 13. A transverse wave is represented by y = 2sin ? ? t kx ?? cm. The value of wavelength (in cm) for which the wave velocity becomes equal to the maximum particle velocity, will be ; (A) 4 ? (B) 2 ? (C) ? (D) 2 Official Ans. by NTA (A) Sol. y = 2 sin ( ?t – kx) Maximum particle velocity = A ? ? ? Wave velocity = k ? k ? = A ? ? ? k = 1 A = 2 ? ? ? = 2 ?A = 4 ? cm ? Page 4 1 FINAL JEE –MAIN EXAMINATION – JULY, 2022 (Held On Tuesday 26 th July, 2022) TIME : 3 : 00 PM to 6 : 00 PM PHYSICS TEST PAPER WITH SOLUTION SECTION-A 1. Two projectiles are thrown with same initial velocity making an angle of 45° and 30° with the horizontal respectively. The ratio of their respective ranges will be (A) 1: 2 (B) 2 :1 (C) 2: 3 (D) 3 :2 Official Ans. by NTA (C) Sol. Let projection speed is u 22 12 u S i n( 9 0 º ) u s i n ( 6 0 º ) R ;R gg ?? 1 2 R 2 R 3 ? 2. In a Vernier Calipers. 10 divisions of Vernier scale is equal to the 9 divisions of main scale. When both jaws of Vernier calipers touch each other, the zero of the Vernier scale is shifted to the left of zero of the main scale and 4 th Vernier scale division exactly coincides with the main scale reading. One main scale division is equal to 1 mm. While measuring diameter of a spherical body, the body is held between two jaws. It is now observed that zero of the Vernier scale lies between 30 and 31 divisions of main scale reading and 6 th Vernier scale division exactly. coincides with the main scale reading. The diameter of the spherical body will be : (A) 3.02 cm (B) 3.06 cm (C) 3.10 cm (D) 3.20 cm Official Ans. by NTA (C) Sol. 1 M.S.D = 1mm 9 M.S.D = 10 V.S.D 1 V.S.D = 0.9 M.S.D = 0.9 mm L.C of vernier caliper = 1–0.9 = 0.1 mm = 0.01 cm zero error =–(10–4)×0.1mm = – 0.6 mm Reading = M.S.R + V.S.R – Zero error = 3cm + 6 × 0.01 – [–0.06] = 3 + 0.06 + 0.06 = 3.12 cm Nearest given answer in the options is 3.10 3. A ball of mass 0.15 kg hits the wall with its initial speed of 12 ms -1 and bounces back without changing its initial speed. If the force applied by the wall on the ball during the contact is 100 N. calculate the time duration of the contact of ball with the wall. (A) 0.018 s (B) 0.036 s (C) 0.009 s (D) 0.072 s Official Ans. by NTA (B) Sol. ? ? i ˆ P 0.15 12 i ?? ? ? f ˆ P 0.15 12 i ? ? ? P 3.6 kg m / s ? ? ? 3.6 = F ? t 3.6 = 100 ? t ? t = 0.036 sec 4. A body of mass 8 kg and another of mass 2 kg are moving with equal kinetic energy. The ratio of their respective momenta will be : (A) 1:1 (B) 2:1 (C) 1:4 (D) 4:1 Official Ans. by NTA (B) Sol. K.E = 2 P 2m ? ? 2 1 1 P K 28 ? ; ? ? 2 2 2 P K 22 ? K 1 = K 2 So, 4P 2 2 = P 1 2 1 2 P 2 P ? 5. Two uniformly charged spherical conductors A and B of radii 5 mm and 10 mm are separated by a distance of 2 cm. If the spheres are connected by a conducting wire, then in equilibrium condition, the ratio of the magnitudes of the electric fields at the surface of the sphere A and B will be : (A) 1 : 2 (B) 2 : 1 (C) 1 : 1 (D) 1 : 4 Official Ans. by NTA (B) 2 Sol. V A = V B AB AB KQ KQ RR ? AA BB QR 1 Q R 2 ?? AB AB22 AB KQ KQ E ;E RR ?? 2 A A B B 2 B B A A E Q R R 2 E Q R R 1 ? ? ? ? 6. The oscillating magnetic field in a plane electromagnetic wave is given by B y = 5 × l0 -6 sin l000 ? (5x - 4 × 10 8 t)T. The amplitude of electric field will be : (A) 15 × 10 2 Vm –1 (B) 5 × 10 –6 Vm –1 (C) 16 × 10 12 Vm –1 (D) 4 × 10 2 Vm –1 Official Ans. by NTA (D) Sol. B 0 =5×10 –6 v = Speed of wave = 8 7 4 10 8 10 5 ? ?? w v k ?? ?? ?? ?? E 0 = vB 0 = 40×10 1 = 4 × 10 2 V/m 7. Light travels in two media M 1 and M 2 with speeds 1.5 × 10 8 ms –1 and 2.0 × 10 8 ms –1 respectively. The critical angle between them is: (A) 1 3 tan 7 ? ?? ?? ?? (B) 1 2 tan 3 ? ?? ?? ?? (C) 1 3 cos 4 ? ?? ?? ?? (D) 1 2 sin 3 ? ?? ?? ?? Official Ans. by NTA (A) Sol. c v n ? n d sin i c = n r sin90º sin i c = d r dr v n nv ? sin i c 8 8 1.5 10 1.5 2 10 2 ? ?? ? c 3 sin i 4 ? tan i c = 22 33 7 43 ? ? i c = 1 3 tan 7 ? ?? ?? ?? 8. A body is projected vertically upwards from the surface of earth with a velocity equal to one third of escape velocity. The maximum height attained by the body will be: (Take radius of earth = 6400 km and g=10 ms –2 ) (A) 800 km (B) 1600 km (C) 2133 km (D) 4800 km Official Ans. by NTA (A) Sol. e 2Gm v R ? 2 e V GMm 1 GMm m R 2 9 R h ? ? ? ? ? 2 e V GM GM R h R 18 ?? ? GM GM GM R h R 9R ?? ? GM 8GM R h 9R ? ? 18 R h 9R ? ? 9R = 8R + 8h R 6400 h 800km 88 ? ? ? 9. The maximum and minimum voltage of an amplitude modulated signal are 60 V and 20 V respectively. The percentage modulation index will be : (A) 0.5% (B) 50% (C) 2% (D) 30% Official Ans. by NTA (B) 3 Sol. V max = 60 V min = 20 % modulation = max min max min VV 60 20 40 100 100 100 V V 60 20 80 ?? ? ? ? ? ? ? ?? ?? ? ? ? ? ?? ? ? ? ? ?? ? 50% 10. A nucleus of mass M at rest splits into two parts having masses M' 3 and ? ? 2M' M' M 3 ? . The ratio of de Broglie wavelength of two parts will be : (A) 1 : 2 (B) 2 : 1 (C) 1 : 1 (D) 2 : 3 Official Ans. by NTA (C) Sol. 12 PP ? Here P is momentum So h P ?? Hence both will have same de broglie wavelength. 11. An ice cube of dimensions 60 cm × 50 cm × 20 cm is placed in an insulation box of wall thickness 1 cm. The box keeping the ice cube at 0°C of temperature is brought to a room of temperature 40°C. The rate of melting of ice is approximately: (Latent heat of fusion of ice is 3.4 × 10 5 J kg –1 and thermal conducting of insulation wall is 0.05 Wm –1 ºC –1 ) (A) 61×10 –1 kg s –1 (B) 61×10 –5 kg s –1 (C) 208 kg s –1 (D) 30×10 –5 kg s –1 Official Ans. by NTA (B) Sol. dQ KA T dt ? ? A = 2 (0.6 × 0.5 + 0.5 × 0.2 + 0.2 × 0.6) = 2(0.3 + 0.1 + 0.12) = 2(0.4 + 0.12) = 2(0.52) = 1.04 m 2 R th = 22 1 10 10 KA 0.05 1.04 0.052 ?? ? ?? ? 2 2 th dQ T 40 0.052 2.08 10 J / s dt R 10 ? ?? ? ? ? ? 2.08 × 10 2 = m × 3.4 × 10 5 m = 3 3 2.08 0.61 10 3.4 10 ? ?? ? kg/s = 61 × 10 –5 Kg/s 12. A gas has n degrees of freedom. The ratio of specific heat of gas at constant volume to the specific heat of gas at constant pressure will be : (A) n n2 ? (B) n2 n ? (C) n 2n 2 ? (D) n n2 ? Official Ans. by NTA (A) Sol. v nR C 2 ? ? ? p n 2 R C 2 ? ? v p C n C n 2 ? ? 13. A transverse wave is represented by y = 2sin ? ? t kx ?? cm. The value of wavelength (in cm) for which the wave velocity becomes equal to the maximum particle velocity, will be ; (A) 4 ? (B) 2 ? (C) ? (D) 2 Official Ans. by NTA (A) Sol. y = 2 sin ( ?t – kx) Maximum particle velocity = A ? ? ? Wave velocity = k ? k ? = A ? ? ? k = 1 A = 2 ? ? ? = 2 ?A = 4 ? cm ? 4 14. A battery of 6 V is connected to the circuit as shown below. The current I drawn from the battery is : (A) 1A (B) 2A (C) 6 A 11 (D) 4 A 3 Official Ans. by NTA (A) Sol. Balanced wheat stone bridge in circuit so there is no current in 5 ? ?resistor so it can be removed from the circuit. eq 6 12 R2 6 12 ? ?? ? 6 12 2 18 ? ?? eq R6 ?? eq V6 I 1 Amp. R6 ? ? ? 15. A source of potential difference V is connected to the combination of two identical capacitors as shown in the figure. When key 'K’ is closed, the total energy stored across the combination is E 1 . Now key ‘K’ is opened and dielectric of dielectric constant 5 is introduced between the plates of the capacitors. The total energy stored across the combination is now E 2 . The ratio E 1 /E 2 will be : (A) 1 10 (B) 2 5 (C) 5 13 (D) 5 26 Official Ans. by NTA (C) Sol. (1) Switch is closed C eq = 2C Energy 2 1 eq 1 E C V 2 ? = 2 1 2C V 2 ? E 1 = CV 2 (ii) When switch is opened charge on right capacitor remain CV while potential on left capacitor remain same Dielectric K = 5 C ’ = KC C ’ = 5C ? ? ? ? ? ? 2 2 2 CV 1 E 5C V 2 2 5C ?? 22 2 5CV CV E 2 10 ?? Page 5 1 FINAL JEE –MAIN EXAMINATION – JULY, 2022 (Held On Tuesday 26 th July, 2022) TIME : 3 : 00 PM to 6 : 00 PM PHYSICS TEST PAPER WITH SOLUTION SECTION-A 1. Two projectiles are thrown with same initial velocity making an angle of 45° and 30° with the horizontal respectively. The ratio of their respective ranges will be (A) 1: 2 (B) 2 :1 (C) 2: 3 (D) 3 :2 Official Ans. by NTA (C) Sol. Let projection speed is u 22 12 u S i n( 9 0 º ) u s i n ( 6 0 º ) R ;R gg ?? 1 2 R 2 R 3 ? 2. In a Vernier Calipers. 10 divisions of Vernier scale is equal to the 9 divisions of main scale. When both jaws of Vernier calipers touch each other, the zero of the Vernier scale is shifted to the left of zero of the main scale and 4 th Vernier scale division exactly coincides with the main scale reading. One main scale division is equal to 1 mm. While measuring diameter of a spherical body, the body is held between two jaws. It is now observed that zero of the Vernier scale lies between 30 and 31 divisions of main scale reading and 6 th Vernier scale division exactly. coincides with the main scale reading. The diameter of the spherical body will be : (A) 3.02 cm (B) 3.06 cm (C) 3.10 cm (D) 3.20 cm Official Ans. by NTA (C) Sol. 1 M.S.D = 1mm 9 M.S.D = 10 V.S.D 1 V.S.D = 0.9 M.S.D = 0.9 mm L.C of vernier caliper = 1–0.9 = 0.1 mm = 0.01 cm zero error =–(10–4)×0.1mm = – 0.6 mm Reading = M.S.R + V.S.R – Zero error = 3cm + 6 × 0.01 – [–0.06] = 3 + 0.06 + 0.06 = 3.12 cm Nearest given answer in the options is 3.10 3. A ball of mass 0.15 kg hits the wall with its initial speed of 12 ms -1 and bounces back without changing its initial speed. If the force applied by the wall on the ball during the contact is 100 N. calculate the time duration of the contact of ball with the wall. (A) 0.018 s (B) 0.036 s (C) 0.009 s (D) 0.072 s Official Ans. by NTA (B) Sol. ? ? i ˆ P 0.15 12 i ?? ? ? f ˆ P 0.15 12 i ? ? ? P 3.6 kg m / s ? ? ? 3.6 = F ? t 3.6 = 100 ? t ? t = 0.036 sec 4. A body of mass 8 kg and another of mass 2 kg are moving with equal kinetic energy. The ratio of their respective momenta will be : (A) 1:1 (B) 2:1 (C) 1:4 (D) 4:1 Official Ans. by NTA (B) Sol. K.E = 2 P 2m ? ? 2 1 1 P K 28 ? ; ? ? 2 2 2 P K 22 ? K 1 = K 2 So, 4P 2 2 = P 1 2 1 2 P 2 P ? 5. Two uniformly charged spherical conductors A and B of radii 5 mm and 10 mm are separated by a distance of 2 cm. If the spheres are connected by a conducting wire, then in equilibrium condition, the ratio of the magnitudes of the electric fields at the surface of the sphere A and B will be : (A) 1 : 2 (B) 2 : 1 (C) 1 : 1 (D) 1 : 4 Official Ans. by NTA (B) 2 Sol. V A = V B AB AB KQ KQ RR ? AA BB QR 1 Q R 2 ?? AB AB22 AB KQ KQ E ;E RR ?? 2 A A B B 2 B B A A E Q R R 2 E Q R R 1 ? ? ? ? 6. The oscillating magnetic field in a plane electromagnetic wave is given by B y = 5 × l0 -6 sin l000 ? (5x - 4 × 10 8 t)T. The amplitude of electric field will be : (A) 15 × 10 2 Vm –1 (B) 5 × 10 –6 Vm –1 (C) 16 × 10 12 Vm –1 (D) 4 × 10 2 Vm –1 Official Ans. by NTA (D) Sol. B 0 =5×10 –6 v = Speed of wave = 8 7 4 10 8 10 5 ? ?? w v k ?? ?? ?? ?? E 0 = vB 0 = 40×10 1 = 4 × 10 2 V/m 7. Light travels in two media M 1 and M 2 with speeds 1.5 × 10 8 ms –1 and 2.0 × 10 8 ms –1 respectively. The critical angle between them is: (A) 1 3 tan 7 ? ?? ?? ?? (B) 1 2 tan 3 ? ?? ?? ?? (C) 1 3 cos 4 ? ?? ?? ?? (D) 1 2 sin 3 ? ?? ?? ?? Official Ans. by NTA (A) Sol. c v n ? n d sin i c = n r sin90º sin i c = d r dr v n nv ? sin i c 8 8 1.5 10 1.5 2 10 2 ? ?? ? c 3 sin i 4 ? tan i c = 22 33 7 43 ? ? i c = 1 3 tan 7 ? ?? ?? ?? 8. A body is projected vertically upwards from the surface of earth with a velocity equal to one third of escape velocity. The maximum height attained by the body will be: (Take radius of earth = 6400 km and g=10 ms –2 ) (A) 800 km (B) 1600 km (C) 2133 km (D) 4800 km Official Ans. by NTA (A) Sol. e 2Gm v R ? 2 e V GMm 1 GMm m R 2 9 R h ? ? ? ? ? 2 e V GM GM R h R 18 ?? ? GM GM GM R h R 9R ?? ? GM 8GM R h 9R ? ? 18 R h 9R ? ? 9R = 8R + 8h R 6400 h 800km 88 ? ? ? 9. The maximum and minimum voltage of an amplitude modulated signal are 60 V and 20 V respectively. The percentage modulation index will be : (A) 0.5% (B) 50% (C) 2% (D) 30% Official Ans. by NTA (B) 3 Sol. V max = 60 V min = 20 % modulation = max min max min VV 60 20 40 100 100 100 V V 60 20 80 ?? ? ? ? ? ? ? ?? ?? ? ? ? ? ?? ? ? ? ? ?? ? 50% 10. A nucleus of mass M at rest splits into two parts having masses M' 3 and ? ? 2M' M' M 3 ? . The ratio of de Broglie wavelength of two parts will be : (A) 1 : 2 (B) 2 : 1 (C) 1 : 1 (D) 2 : 3 Official Ans. by NTA (C) Sol. 12 PP ? Here P is momentum So h P ?? Hence both will have same de broglie wavelength. 11. An ice cube of dimensions 60 cm × 50 cm × 20 cm is placed in an insulation box of wall thickness 1 cm. The box keeping the ice cube at 0°C of temperature is brought to a room of temperature 40°C. The rate of melting of ice is approximately: (Latent heat of fusion of ice is 3.4 × 10 5 J kg –1 and thermal conducting of insulation wall is 0.05 Wm –1 ºC –1 ) (A) 61×10 –1 kg s –1 (B) 61×10 –5 kg s –1 (C) 208 kg s –1 (D) 30×10 –5 kg s –1 Official Ans. by NTA (B) Sol. dQ KA T dt ? ? A = 2 (0.6 × 0.5 + 0.5 × 0.2 + 0.2 × 0.6) = 2(0.3 + 0.1 + 0.12) = 2(0.4 + 0.12) = 2(0.52) = 1.04 m 2 R th = 22 1 10 10 KA 0.05 1.04 0.052 ?? ? ?? ? 2 2 th dQ T 40 0.052 2.08 10 J / s dt R 10 ? ?? ? ? ? ? 2.08 × 10 2 = m × 3.4 × 10 5 m = 3 3 2.08 0.61 10 3.4 10 ? ?? ? kg/s = 61 × 10 –5 Kg/s 12. A gas has n degrees of freedom. The ratio of specific heat of gas at constant volume to the specific heat of gas at constant pressure will be : (A) n n2 ? (B) n2 n ? (C) n 2n 2 ? (D) n n2 ? Official Ans. by NTA (A) Sol. v nR C 2 ? ? ? p n 2 R C 2 ? ? v p C n C n 2 ? ? 13. A transverse wave is represented by y = 2sin ? ? t kx ?? cm. The value of wavelength (in cm) for which the wave velocity becomes equal to the maximum particle velocity, will be ; (A) 4 ? (B) 2 ? (C) ? (D) 2 Official Ans. by NTA (A) Sol. y = 2 sin ( ?t – kx) Maximum particle velocity = A ? ? ? Wave velocity = k ? k ? = A ? ? ? k = 1 A = 2 ? ? ? = 2 ?A = 4 ? cm ? 4 14. A battery of 6 V is connected to the circuit as shown below. The current I drawn from the battery is : (A) 1A (B) 2A (C) 6 A 11 (D) 4 A 3 Official Ans. by NTA (A) Sol. Balanced wheat stone bridge in circuit so there is no current in 5 ? ?resistor so it can be removed from the circuit. eq 6 12 R2 6 12 ? ?? ? 6 12 2 18 ? ?? eq R6 ?? eq V6 I 1 Amp. R6 ? ? ? 15. A source of potential difference V is connected to the combination of two identical capacitors as shown in the figure. When key 'K’ is closed, the total energy stored across the combination is E 1 . Now key ‘K’ is opened and dielectric of dielectric constant 5 is introduced between the plates of the capacitors. The total energy stored across the combination is now E 2 . The ratio E 1 /E 2 will be : (A) 1 10 (B) 2 5 (C) 5 13 (D) 5 26 Official Ans. by NTA (C) Sol. (1) Switch is closed C eq = 2C Energy 2 1 eq 1 E C V 2 ? = 2 1 2C V 2 ? E 1 = CV 2 (ii) When switch is opened charge on right capacitor remain CV while potential on left capacitor remain same Dielectric K = 5 C ’ = KC C ’ = 5C ? ? ? ? ? ? 2 2 2 CV 1 E 5C V 2 2 5C ?? 22 2 5CV CV E 2 10 ?? 5 2 2 13CV E 5 ? 2 1 2 2 E CV 5 13CV E 13 5 ?? 1 2 E 5 E 13 ? 16. Two concentric circular loops of radii r 1 =30 cm and r 2 =50 cm are placed in X-Y plane as shown in the figure. A current I = 7A is flowing through them in the direction as shown in figure. The net magnetic moment of this system of two circular loops is approximately : (A) 2 7 ˆ k Am 2 (B) 2 7 ˆ k Am 2 ? (C) 2 ˆ 7k Am (D) – 2 ˆ 7 k Am Official Ans. by NTA (B) Sol. Magnetic moment ? ? ? ? 22 ˆˆ M i 0.5 k i 0.3 k ? ? ? ? ? 22 25 9 ˆ M 7 k 7 100 100 ?? ? ? ? ? ?? ?? = 16 ˆ 22 k 100 ?? ? ?? ?? ˆ M 3.52k ?? Am 2 7 ˆ k 2 ?? Am 2 17. A velocity selector consists of electric field ˆ E Ek ? and magnetic field ˆ B Bj ? with B=12 mT. The value E required for an electron of energy 728 eV moving along the positive x-axis to pass undeflected is : (Given, mass of electron = 9.1×10 –31 kg) (A) 192 kVm –1 (B) 192 m Vm –1 (C) 9600 kVm –1 (D) 16 kVm –1 Official Ans. by NTA (A) Sol. ˆ E E k ? B = 12 mT ˆ B B j ? Energy = 728 eV Energy = 2 1 mv 2 31 2 1 728eV 9.1 10 v 2 ? ? ? ? ? 19 31 2 1 728 1.6 10 9.1 10 v 2 ?? ? ? ? ? ? ? v = 16 × 10 6 m/s E = vB E = 16×10 6 × 12 × 10 –3 E = 192 × 10 3 V/m 18. Two masses M 1 and .M 2 are tied together at the two ends of a light inextensible string that passes over a frictionless pulley. When the mass M 2 is twice that of M 1 . the acceleration of the system is a 1 . When the mass M 2 is thrice that of M 1 . The acceleration of The system is a 2 . The ratio 1 2 a a will be: (A) 1 3 (B) 2 3 (C) 3 2 (D) 1 2 Official Ans. by NTA (B) Sol. 21 12 m g m g a mm ? ? ? Case 1 M 2 = 2m 1 a 1 = 11 1 2m g m g 3m ? a 1 = g/3Read More
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