JEE Main 2021 Physics March 18 Shift 1 Paper & Solutions | Mock Tests for JEE Main and Advanced 2025 PDF Download

 Page 1


 
 
18
th
 March 2021 | Shift 1
SECTION – A 
 
1. In a series LCR resonance circuit, if we change the resistance only, from a lower to higher value : 
 (1) The resonance frequency will increase    
 (2) The quality factor will increase 
  (3) The quality factor and the resonance frequency will remain constant  
  (4) The bandwidth of resonance circuit will increase  
1. (4)  
Sol. ?
f
 = 
1
LC
 frequency will not change 
 Q = 
L
R
?
R Q ? ? 
 Q = 
L
R B
? ?
?
?
 
 ? ? = 
R
L
R B ? ? ? 
 So, band with of resonance circuit will increases. 
 By Motion Ans ? 4 
 By NTA Ans ? 4  
 
2. A radioactive sample disintegrates via two independent decay processes having half lives 
? ? 1
1
2
T 
and 
? ? 2
1
2
T respectively. The effective half-life, 
1
2
T of the nuclei is: 
 (1) None of the above (2) 
? ? ? ?
? ?
1 2
1 1 1
2 2 2
T T T 
  (3) 
? ? ? ?
? ? ? ?
?
?
?
1 2
1 1
2 2
1
1 2
2
1 1
2 2
T T
T
T T
   (4)  
? ? ? ?
? ? ? ?
?
?
1 2
1 1
2 2
1
1 2
2
1 1
2 2
T T
T
T T
 
2. (4) 
Sol. 
? ?
? ?
? ?
? ?
1
1
dN
N
dt
, 
? ?
? ?
? ?
? ?
2
2
dN
N
dt
 
 
dN
dt
=
1 2
dN dN
dt dt
? ? ? ?
?
? ? ? ?
? ? ? ?
 
 N ?
eff
 = N ?
1
 × N ?
2
 
 
eff
1
T
=
1 2
1 1
T T
? 
 T
eff
 = 
1 2
1 2
T T
T T ?
 
 By Motion Ans ? 4  
 By NTA Ans ? 4  
 
Page 2


 
 
18
th
 March 2021 | Shift 1
SECTION – A 
 
1. In a series LCR resonance circuit, if we change the resistance only, from a lower to higher value : 
 (1) The resonance frequency will increase    
 (2) The quality factor will increase 
  (3) The quality factor and the resonance frequency will remain constant  
  (4) The bandwidth of resonance circuit will increase  
1. (4)  
Sol. ?
f
 = 
1
LC
 frequency will not change 
 Q = 
L
R
?
R Q ? ? 
 Q = 
L
R B
? ?
?
?
 
 ? ? = 
R
L
R B ? ? ? 
 So, band with of resonance circuit will increases. 
 By Motion Ans ? 4 
 By NTA Ans ? 4  
 
2. A radioactive sample disintegrates via two independent decay processes having half lives 
? ? 1
1
2
T 
and 
? ? 2
1
2
T respectively. The effective half-life, 
1
2
T of the nuclei is: 
 (1) None of the above (2) 
? ? ? ?
? ?
1 2
1 1 1
2 2 2
T T T 
  (3) 
? ? ? ?
? ? ? ?
?
?
?
1 2
1 1
2 2
1
1 2
2
1 1
2 2
T T
T
T T
   (4)  
? ? ? ?
? ? ? ?
?
?
1 2
1 1
2 2
1
1 2
2
1 1
2 2
T T
T
T T
 
2. (4) 
Sol. 
? ?
? ?
? ?
? ?
1
1
dN
N
dt
, 
? ?
? ?
? ?
? ?
2
2
dN
N
dt
 
 
dN
dt
=
1 2
dN dN
dt dt
? ? ? ?
?
? ? ? ?
? ? ? ?
 
 N ?
eff
 = N ?
1
 × N ?
2
 
 
eff
1
T
=
1 2
1 1
T T
? 
 T
eff
 = 
1 2
1 2
T T
T T ?
 
 By Motion Ans ? 4  
 By NTA Ans ? 4  
 
 
 
3. In the experiment of Ohm's law, a potential difference of 5.0 V is applied across the end of a 
conductor of length 10.0 cm and diameter of 5.00mm. The measured current in the conductor is 
2.00 A. The maximum permissible percentage error in the resistivity of the conductor is: 
 (1)7.5  (2)3.9  (3)8.4  (4)3.0  
3. (2)  
Sol. V = IR 
 R = ?
A
?
 
 V = 
? ? ?
? ?
? ?
I
A
?
 
 
? = 
VA
I ?
 
 
? ?
?
=
V I d
2
V I d
? ? ? ?
? ? ?
?
?
 
 = 
0.1 0.01 0.1 0.01
2
5 2 10 5
? ? ? ? 
 
? ?
?
=0.02 + 0.005 + 0.01 + 0.004 
 0.039
? ?
?
?
 
 100
? ?
?
?
= 0.039 × 100 = 3.9% 
 By Motion Ans ? 4  
 By NTA Ans ? 4  
 
4. An AC source rated 220V, 50 Hz is connected to a resistor. The time taken by the current to 
change from its maximum to the rms value is: 
 (1) 0.25 ms (2) 25 ms  (3)2.5 ms  (4)2.5 s  
4. (3)  
 
 
t
1
t
2
 
V
peak
V
RMS
 
 V = V
0
 sin ?t = ? ?
1
220 2 sin 2 t ? ?
 
 
? ? ? ?
1
220 2 220 2 sin 100 t
 
 
 V = ? ?
1
220 2 sin 100 t ? 
 1 = sin (100 ?t
1
) 
 
?
? ?
1
100 t
2
 
 t
1
 = 
1
200
 
Page 3


 
 
18
th
 March 2021 | Shift 1
SECTION – A 
 
1. In a series LCR resonance circuit, if we change the resistance only, from a lower to higher value : 
 (1) The resonance frequency will increase    
 (2) The quality factor will increase 
  (3) The quality factor and the resonance frequency will remain constant  
  (4) The bandwidth of resonance circuit will increase  
1. (4)  
Sol. ?
f
 = 
1
LC
 frequency will not change 
 Q = 
L
R
?
R Q ? ? 
 Q = 
L
R B
? ?
?
?
 
 ? ? = 
R
L
R B ? ? ? 
 So, band with of resonance circuit will increases. 
 By Motion Ans ? 4 
 By NTA Ans ? 4  
 
2. A radioactive sample disintegrates via two independent decay processes having half lives 
? ? 1
1
2
T 
and 
? ? 2
1
2
T respectively. The effective half-life, 
1
2
T of the nuclei is: 
 (1) None of the above (2) 
? ? ? ?
? ?
1 2
1 1 1
2 2 2
T T T 
  (3) 
? ? ? ?
? ? ? ?
?
?
?
1 2
1 1
2 2
1
1 2
2
1 1
2 2
T T
T
T T
   (4)  
? ? ? ?
? ? ? ?
?
?
1 2
1 1
2 2
1
1 2
2
1 1
2 2
T T
T
T T
 
2. (4) 
Sol. 
? ?
? ?
? ?
? ?
1
1
dN
N
dt
, 
? ?
? ?
? ?
? ?
2
2
dN
N
dt
 
 
dN
dt
=
1 2
dN dN
dt dt
? ? ? ?
?
? ? ? ?
? ? ? ?
 
 N ?
eff
 = N ?
1
 × N ?
2
 
 
eff
1
T
=
1 2
1 1
T T
? 
 T
eff
 = 
1 2
1 2
T T
T T ?
 
 By Motion Ans ? 4  
 By NTA Ans ? 4  
 
 
 
3. In the experiment of Ohm's law, a potential difference of 5.0 V is applied across the end of a 
conductor of length 10.0 cm and diameter of 5.00mm. The measured current in the conductor is 
2.00 A. The maximum permissible percentage error in the resistivity of the conductor is: 
 (1)7.5  (2)3.9  (3)8.4  (4)3.0  
3. (2)  
Sol. V = IR 
 R = ?
A
?
 
 V = 
? ? ?
? ?
? ?
I
A
?
 
 
? = 
VA
I ?
 
 
? ?
?
=
V I d
2
V I d
? ? ? ?
? ? ?
?
?
 
 = 
0.1 0.01 0.1 0.01
2
5 2 10 5
? ? ? ? 
 
? ?
?
=0.02 + 0.005 + 0.01 + 0.004 
 0.039
? ?
?
?
 
 100
? ?
?
?
= 0.039 × 100 = 3.9% 
 By Motion Ans ? 4  
 By NTA Ans ? 4  
 
4. An AC source rated 220V, 50 Hz is connected to a resistor. The time taken by the current to 
change from its maximum to the rms value is: 
 (1) 0.25 ms (2) 25 ms  (3)2.5 ms  (4)2.5 s  
4. (3)  
 
 
t
1
t
2
 
V
peak
V
RMS
 
 V = V
0
 sin ?t = ? ?
1
220 2 sin 2 t ? ?
 
 
? ? ? ?
1
220 2 220 2 sin 100 t
 
 
 V = ? ?
1
220 2 sin 100 t ? 
 1 = sin (100 ?t
1
) 
 
?
? ?
1
100 t
2
 
 t
1
 = 
1
200
 
 
 
18
th
 March 2021 | Shift 1
 
200
200 2
=sin ( ?t
2
) 
 
2
2 t
4
?
? ? ? 
 t
2
 = 
1
400
 
 
1 2
1 1
t t t
200 400
? ? ? ? ? 
 
1
t sec 2.5ms
400
? ? ? 
 IInd Method 
 Phase different b/w 
 Max & RMS = 
4
?
 
 So, ?t = T/8 
 
1 1
t sec
8 50 400
? ? ?
?
 
 t 2.5ms ? ? 
 
5. Four identical long solenoids A, B, C and D are connected to each other as shown in the figure. 
If the magnetic field at the center of A is 3 T, the field at the center of C would be: 
 (Assume that the magnetic field is confined with in the volume of respective solenoid.) 
 
 
B 
D
C 
A
i
 
 (1) 6T (2) 12T  (3) 1T  (4) 9T  
5. (3) 
 
 
B
D
C
3T
I
2
I
3
I
1
 
 3I
1
 = I
0
 
 I
1
 = 
0
I
3
 
 B = ?
0
 nI
0
 = 3T 
 ? ?
1 0 1
B nI
 
 B
'
 = µ
0
n
0
I
3
 = 
0
µ x70 3T
1T
3 3
? ?
 
Page 4


 
 
18
th
 March 2021 | Shift 1
SECTION – A 
 
1. In a series LCR resonance circuit, if we change the resistance only, from a lower to higher value : 
 (1) The resonance frequency will increase    
 (2) The quality factor will increase 
  (3) The quality factor and the resonance frequency will remain constant  
  (4) The bandwidth of resonance circuit will increase  
1. (4)  
Sol. ?
f
 = 
1
LC
 frequency will not change 
 Q = 
L
R
?
R Q ? ? 
 Q = 
L
R B
? ?
?
?
 
 ? ? = 
R
L
R B ? ? ? 
 So, band with of resonance circuit will increases. 
 By Motion Ans ? 4 
 By NTA Ans ? 4  
 
2. A radioactive sample disintegrates via two independent decay processes having half lives 
? ? 1
1
2
T 
and 
? ? 2
1
2
T respectively. The effective half-life, 
1
2
T of the nuclei is: 
 (1) None of the above (2) 
? ? ? ?
? ?
1 2
1 1 1
2 2 2
T T T 
  (3) 
? ? ? ?
? ? ? ?
?
?
?
1 2
1 1
2 2
1
1 2
2
1 1
2 2
T T
T
T T
   (4)  
? ? ? ?
? ? ? ?
?
?
1 2
1 1
2 2
1
1 2
2
1 1
2 2
T T
T
T T
 
2. (4) 
Sol. 
? ?
? ?
? ?
? ?
1
1
dN
N
dt
, 
? ?
? ?
? ?
? ?
2
2
dN
N
dt
 
 
dN
dt
=
1 2
dN dN
dt dt
? ? ? ?
?
? ? ? ?
? ? ? ?
 
 N ?
eff
 = N ?
1
 × N ?
2
 
 
eff
1
T
=
1 2
1 1
T T
? 
 T
eff
 = 
1 2
1 2
T T
T T ?
 
 By Motion Ans ? 4  
 By NTA Ans ? 4  
 
 
 
3. In the experiment of Ohm's law, a potential difference of 5.0 V is applied across the end of a 
conductor of length 10.0 cm and diameter of 5.00mm. The measured current in the conductor is 
2.00 A. The maximum permissible percentage error in the resistivity of the conductor is: 
 (1)7.5  (2)3.9  (3)8.4  (4)3.0  
3. (2)  
Sol. V = IR 
 R = ?
A
?
 
 V = 
? ? ?
? ?
? ?
I
A
?
 
 
? = 
VA
I ?
 
 
? ?
?
=
V I d
2
V I d
? ? ? ?
? ? ?
?
?
 
 = 
0.1 0.01 0.1 0.01
2
5 2 10 5
? ? ? ? 
 
? ?
?
=0.02 + 0.005 + 0.01 + 0.004 
 0.039
? ?
?
?
 
 100
? ?
?
?
= 0.039 × 100 = 3.9% 
 By Motion Ans ? 4  
 By NTA Ans ? 4  
 
4. An AC source rated 220V, 50 Hz is connected to a resistor. The time taken by the current to 
change from its maximum to the rms value is: 
 (1) 0.25 ms (2) 25 ms  (3)2.5 ms  (4)2.5 s  
4. (3)  
 
 
t
1
t
2
 
V
peak
V
RMS
 
 V = V
0
 sin ?t = ? ?
1
220 2 sin 2 t ? ?
 
 
? ? ? ?
1
220 2 220 2 sin 100 t
 
 
 V = ? ?
1
220 2 sin 100 t ? 
 1 = sin (100 ?t
1
) 
 
?
? ?
1
100 t
2
 
 t
1
 = 
1
200
 
 
 
18
th
 March 2021 | Shift 1
 
200
200 2
=sin ( ?t
2
) 
 
2
2 t
4
?
? ? ? 
 t
2
 = 
1
400
 
 
1 2
1 1
t t t
200 400
? ? ? ? ? 
 
1
t sec 2.5ms
400
? ? ? 
 IInd Method 
 Phase different b/w 
 Max & RMS = 
4
?
 
 So, ?t = T/8 
 
1 1
t sec
8 50 400
? ? ?
?
 
 t 2.5ms ? ? 
 
5. Four identical long solenoids A, B, C and D are connected to each other as shown in the figure. 
If the magnetic field at the center of A is 3 T, the field at the center of C would be: 
 (Assume that the magnetic field is confined with in the volume of respective solenoid.) 
 
 
B 
D
C 
A
i
 
 (1) 6T (2) 12T  (3) 1T  (4) 9T  
5. (3) 
 
 
B
D
C
3T
I
2
I
3
I
1
 
 3I
1
 = I
0
 
 I
1
 = 
0
I
3
 
 B = ?
0
 nI
0
 = 3T 
 ? ?
1 0 1
B nI
 
 B
'
 = µ
0
n
0
I
3
 = 
0
µ x70 3T
1T
3 3
? ?
 
 
 
 B
'
 = 1T 
 By Motion Ans ? 1
 
 By NTA Ans ? 1
 
 
6. A plane electromagnetic wave of frequency 100 MHz is travelling in vacuum along the x- 
direction. At a particular point in space and time, 
–8
ˆ
B 2.0 10 kT ? ?
?
 (where, 
ˆ
k is unit vector along z-
direction). What is E
?
 at this point ? (speed of light c = 3 × 10
8
 m/s) 
 (1) 0.6 
ˆ
j V/m (2) 6.0
ˆ
k V/m  (3) 6.0 
ˆ
j V/m  (4) 0.6 
ˆ
k V/m  
6. (3) 
f = 100 MHz 
 
 
v=3×10
8
 
ˆ
i
8
B 2 10 T
?
? ?
?
 
 E B V ? ?
? ? ?
 
 = (2 × 10
-8
 
ˆ
k ) × (3 × 10
8
 
ˆ
i ) 
 = 6 
? ?
ˆ ˆ
k i ? = 
ˆ
6j V/m 
 
ˆ
E 6j ?
?
V/m 
 By motion Ans ? 3 
 By NTA Ans  ? 3 
 
7. A particle is travelling, 4 times as fast as an electron. Assuming the ratio of de-Broglie 
wavelength of a particle to that of electron is 2:1, the mass of the particle is : 
 (1) 
1
16
 times of mass of e
–
 (2) 16 times the mass of e
–
   
 (3) 
1
8
 times the mass of e
–
  (4)  8 times the mass of e
– 
7. (3) 
h h
p mv
? ? ? 
 
p p p
e e
e p p
e e
h
m v
m v
h
m v
m v
?
? ?
?
 
 
e e
p e
M v 2
1 M 4v
? ? 
 
e
p
M
m
8
? 
 
1
8
 times the mass of electron 
 By Motion Ans ? 3 
 By NTA Ans ? 3 
 
Page 5


 
 
18
th
 March 2021 | Shift 1
SECTION – A 
 
1. In a series LCR resonance circuit, if we change the resistance only, from a lower to higher value : 
 (1) The resonance frequency will increase    
 (2) The quality factor will increase 
  (3) The quality factor and the resonance frequency will remain constant  
  (4) The bandwidth of resonance circuit will increase  
1. (4)  
Sol. ?
f
 = 
1
LC
 frequency will not change 
 Q = 
L
R
?
R Q ? ? 
 Q = 
L
R B
? ?
?
?
 
 ? ? = 
R
L
R B ? ? ? 
 So, band with of resonance circuit will increases. 
 By Motion Ans ? 4 
 By NTA Ans ? 4  
 
2. A radioactive sample disintegrates via two independent decay processes having half lives 
? ? 1
1
2
T 
and 
? ? 2
1
2
T respectively. The effective half-life, 
1
2
T of the nuclei is: 
 (1) None of the above (2) 
? ? ? ?
? ?
1 2
1 1 1
2 2 2
T T T 
  (3) 
? ? ? ?
? ? ? ?
?
?
?
1 2
1 1
2 2
1
1 2
2
1 1
2 2
T T
T
T T
   (4)  
? ? ? ?
? ? ? ?
?
?
1 2
1 1
2 2
1
1 2
2
1 1
2 2
T T
T
T T
 
2. (4) 
Sol. 
? ?
? ?
? ?
? ?
1
1
dN
N
dt
, 
? ?
? ?
? ?
? ?
2
2
dN
N
dt
 
 
dN
dt
=
1 2
dN dN
dt dt
? ? ? ?
?
? ? ? ?
? ? ? ?
 
 N ?
eff
 = N ?
1
 × N ?
2
 
 
eff
1
T
=
1 2
1 1
T T
? 
 T
eff
 = 
1 2
1 2
T T
T T ?
 
 By Motion Ans ? 4  
 By NTA Ans ? 4  
 
 
 
3. In the experiment of Ohm's law, a potential difference of 5.0 V is applied across the end of a 
conductor of length 10.0 cm and diameter of 5.00mm. The measured current in the conductor is 
2.00 A. The maximum permissible percentage error in the resistivity of the conductor is: 
 (1)7.5  (2)3.9  (3)8.4  (4)3.0  
3. (2)  
Sol. V = IR 
 R = ?
A
?
 
 V = 
? ? ?
? ?
? ?
I
A
?
 
 
? = 
VA
I ?
 
 
? ?
?
=
V I d
2
V I d
? ? ? ?
? ? ?
?
?
 
 = 
0.1 0.01 0.1 0.01
2
5 2 10 5
? ? ? ? 
 
? ?
?
=0.02 + 0.005 + 0.01 + 0.004 
 0.039
? ?
?
?
 
 100
? ?
?
?
= 0.039 × 100 = 3.9% 
 By Motion Ans ? 4  
 By NTA Ans ? 4  
 
4. An AC source rated 220V, 50 Hz is connected to a resistor. The time taken by the current to 
change from its maximum to the rms value is: 
 (1) 0.25 ms (2) 25 ms  (3)2.5 ms  (4)2.5 s  
4. (3)  
 
 
t
1
t
2
 
V
peak
V
RMS
 
 V = V
0
 sin ?t = ? ?
1
220 2 sin 2 t ? ?
 
 
? ? ? ?
1
220 2 220 2 sin 100 t
 
 
 V = ? ?
1
220 2 sin 100 t ? 
 1 = sin (100 ?t
1
) 
 
?
? ?
1
100 t
2
 
 t
1
 = 
1
200
 
 
 
18
th
 March 2021 | Shift 1
 
200
200 2
=sin ( ?t
2
) 
 
2
2 t
4
?
? ? ? 
 t
2
 = 
1
400
 
 
1 2
1 1
t t t
200 400
? ? ? ? ? 
 
1
t sec 2.5ms
400
? ? ? 
 IInd Method 
 Phase different b/w 
 Max & RMS = 
4
?
 
 So, ?t = T/8 
 
1 1
t sec
8 50 400
? ? ?
?
 
 t 2.5ms ? ? 
 
5. Four identical long solenoids A, B, C and D are connected to each other as shown in the figure. 
If the magnetic field at the center of A is 3 T, the field at the center of C would be: 
 (Assume that the magnetic field is confined with in the volume of respective solenoid.) 
 
 
B 
D
C 
A
i
 
 (1) 6T (2) 12T  (3) 1T  (4) 9T  
5. (3) 
 
 
B
D
C
3T
I
2
I
3
I
1
 
 3I
1
 = I
0
 
 I
1
 = 
0
I
3
 
 B = ?
0
 nI
0
 = 3T 
 ? ?
1 0 1
B nI
 
 B
'
 = µ
0
n
0
I
3
 = 
0
µ x70 3T
1T
3 3
? ?
 
 
 
 B
'
 = 1T 
 By Motion Ans ? 1
 
 By NTA Ans ? 1
 
 
6. A plane electromagnetic wave of frequency 100 MHz is travelling in vacuum along the x- 
direction. At a particular point in space and time, 
–8
ˆ
B 2.0 10 kT ? ?
?
 (where, 
ˆ
k is unit vector along z-
direction). What is E
?
 at this point ? (speed of light c = 3 × 10
8
 m/s) 
 (1) 0.6 
ˆ
j V/m (2) 6.0
ˆ
k V/m  (3) 6.0 
ˆ
j V/m  (4) 0.6 
ˆ
k V/m  
6. (3) 
f = 100 MHz 
 
 
v=3×10
8
 
ˆ
i
8
B 2 10 T
?
? ?
?
 
 E B V ? ?
? ? ?
 
 = (2 × 10
-8
 
ˆ
k ) × (3 × 10
8
 
ˆ
i ) 
 = 6 
? ?
ˆ ˆ
k i ? = 
ˆ
6j V/m 
 
ˆ
E 6j ?
?
V/m 
 By motion Ans ? 3 
 By NTA Ans  ? 3 
 
7. A particle is travelling, 4 times as fast as an electron. Assuming the ratio of de-Broglie 
wavelength of a particle to that of electron is 2:1, the mass of the particle is : 
 (1) 
1
16
 times of mass of e
–
 (2) 16 times the mass of e
–
   
 (3) 
1
8
 times the mass of e
–
  (4)  8 times the mass of e
– 
7. (3) 
h h
p mv
? ? ? 
 
p p p
e e
e p p
e e
h
m v
m v
h
m v
m v
?
? ?
?
 
 
e e
p e
M v 2
1 M 4v
? ? 
 
e
p
M
m
8
? 
 
1
8
 times the mass of electron 
 By Motion Ans ? 3 
 By NTA Ans ? 3 
 
 
 
18
th
 March 2021 | Shift 1
8. What will be the average value of energy along one degree of freedom for an ideal gas in 
thermal equilibrium at a temperature T? (k
B
 is Boltzmann constant) 
 (1) k
B
T (2) 
B
2
k T
3
 (3) 
B
3
k T
2
 (4) 
B
1
k T
2
 
8. (4) 
Energy associated with each digress of freedom is 
1
2
 K
B
T. 
 By Motion Ans ? 4  
 By NTA Ans ? 4 
 
9. Your friend is having eye sight problem. She is not able to see clearly a distant uniform window 
mesh and it appears to her as non-uniform and distorted. The doctor diagnosed the problem as: 
 (1) Myopia and hypermetropia (2) Astigmatism  
 (3) Myopia with astigmatism (4) presbyopia with astigmatism 
9. (3) 
By theory 
 By motion Ans ? 3  
 By NTA Ans ? 3 
 
10. The time period of a simple pendulum is given by T = 
l
2
g
? . The measured value of the length 
of pendulum is 10 cm known to a 1 mm accuracy. The time for 200 oscillations of the pendulum 
is found to be 100 second using a clock of 1s resolution. The percentage accuracy in the 
determination of 'g' using this pendulum is 'x'. The value of 'x' to the nearest integer is . 
 (1)  5% (2) 4%` (3) 3% (4) 2%  
10. (3) 
T = 
l
2
g
? 
 T
2
 = 
l
2
g
? ?
?
? ?
? ?
 
 g = 2 ? 
2
l
T
 
 
g l 2 T
g l T
? ? ?
? ? 
 
3
2
g 1 10 2 1
g 100 1 10
?
?
? ? ?
? ?
?
 
 
g
0.02 0.01 0.03
g
?
? ? ? 
 
g
100 0.03 100 3%
g
?
? ? ? ? 
g
100 3%
g
?
? ? 
By motion Ans ? 3  
By NTA Ans ? 3