Physics: CUET Mock Test - 4 - CUET MCQ

# Physics: CUET Mock Test - 4 - CUET MCQ

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## 40 Questions MCQ Test CUET Mock Test Series - Physics: CUET Mock Test - 4

Physics: CUET Mock Test - 4 for CUET 2024 is part of CUET Mock Test Series preparation. The Physics: CUET Mock Test - 4 questions and answers have been prepared according to the CUET exam syllabus.The Physics: CUET Mock Test - 4 MCQs are made for CUET 2024 Exam. Find important definitions, questions, notes, meanings, examples, exercises, MCQs and online tests for Physics: CUET Mock Test - 4 below.
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Physics: CUET Mock Test - 4 - Question 1

### A transformer is used to light 100 W 25 volt lamp from 250 Volt ac mains. The current in the main cable is 0.5 A. Calculate the efficiency of the transformer.

Detailed Solution for Physics: CUET Mock Test - 4 - Question 1

Given: Output power (Po) = 100 W; Ip = 0.5 A; Vp = 250 V
Input power (Pi) = Vp × Ip
Pi = 250 × 0.5 = 125 W
Efficiency = (Output power/Input power) × 100%
Efficiency = (100/125) x 100
Efficiency = 80
Therefore, the efficiency of the transformer is 80%.

Physics: CUET Mock Test - 4 - Question 2

### A lens immersed in a transparent liquid is not visible. Under what condition can this happen?

Detailed Solution for Physics: CUET Mock Test - 4 - Question 2

When the refractive index of the liquid is the same as the lens material, no light will be reflected by the lens and hence it will not be visible. So, the lens immersed in a transparent liquid will not be visible.

Physics: CUET Mock Test - 4 - Question 3

### The power in an AC circuit contains an inductor of 30 mH, a capacitor of 300 μF, a resistor of 70 Ω, and an AC source of 24 V, 60 Hz. Calculate the energy dissipated in the circuit in 1000 s.

Detailed Solution for Physics: CUET Mock Test - 4 - Question 3

We know that, Pav = Vrms Irms cos⁡Φ ……1 and cosΦ;= R/Z ....2
In LCR, cosΦ = VR/V = IR/IZ and Irms = Vrms/Z ....3
Substituting 2 and 3 in 1

Given: Vrms = 24 V; Resistance (R) = 70 Ω; Inductance (I) = 30 mH = 20 × 10-3 H; Capacitance (C) = 300 μF
X= 2πυL = 2π (60)(30 × 10-3)
XL= 11.304 Ω
XC = (1/(2πvC)) = (1/(2π(60)(300×10−6)))
XC = 8.846 Ω
For series LCR circuit → Z =

Z = 70.04 ≈ 70 Ω
So, the energy used in 1000 seconds is → Pavt =

Therefore, the energy dissipated in the circuit at 1000 seconds is 8.22 × 103J.

Physics: CUET Mock Test - 4 - Question 4

In a step-down transformer, the number of turns in the secondary coil is 20 and the number of turns in the primary coil is 100. If the voltage applied to the primary coil is 120 V, then what is the voltage output from the secondary coil?

Detailed Solution for Physics: CUET Mock Test - 4 - Question 4

Given: Ns = 20; Np = 100; Vp = 120 V
For a step-down transformer → Ns/Np = Vs/Vp

Vs = 24 V
Therefore, the voltage output from the secondary coil is 24 V.

Physics: CUET Mock Test - 4 - Question 5

What is the cause of the blue color of the ocean?

Detailed Solution for Physics: CUET Mock Test - 4 - Question 5

The blue color of the ocean is due to the preferential scattering of light by water molecules. This is the underlying reason for many other phenomena such as why the sky is blue or the sky is reddish at the time of sunrise or sunset.

Physics: CUET Mock Test - 4 - Question 6

How many types of spherical refracting surfaces are there?

Detailed Solution for Physics: CUET Mock Test - 4 - Question 6

The portion of a refracting medium, whose curved surface forms the part of a sphere, is known as a spherical refracting surface. Spherical refracting surfaces are of two types, namely, convex refracting spherical surface and concave refracting spherical surface.

Physics: CUET Mock Test - 4 - Question 7

A boy uses spectacles of focal length -50 cm. Name the defect of the vision he is suffering from.

Detailed Solution for Physics: CUET Mock Test - 4 - Question 7

As the focal length is negative, the lens used is concave. When a person is prescribed a concave lens, then the person is considered to be suffering from myopic. Therefore, the boy is suffering from myopia.

Physics: CUET Mock Test - 4 - Question 8

The speed of the yellow light in a certain liquid is 2.4 × 108 m/s. Find the refractive index of the liquid.

Detailed Solution for Physics: CUET Mock Test - 4 - Question 8

μ = c/vt
μ = 3 × (108/2.4) x 108
μ = 1.25

Physics: CUET Mock Test - 4 - Question 9

In Young’s double-slit experiment with monochromatic light, how is fringe width affected, if the screen is moved closer to the slits?

Detailed Solution for Physics: CUET Mock Test - 4 - Question 9

Fringe width is given as:
β = Dλ/d
As the screen is moved closer to the two slits, the distance denoted by D decreases and so fringe width β increase.

Physics: CUET Mock Test - 4 - Question 10

Identify the expression for Bohr’s second postulate.

Detailed Solution for Physics: CUET Mock Test - 4 - Question 10

According to Bohr’s second postulate, an electron revolves around the nucleus of an atom in orbits and, therefore, the angular momentum of the revolution is an integral multiple of (h/2p), where h is the Planck’s constant. Thus, the expression for angular momentum is given as: L = nh/2p

Physics: CUET Mock Test - 4 - Question 11

Which among the following is a portion of a transparent refracting medium bound by one spherical surface and the other plane surface?

Detailed Solution for Physics: CUET Mock Test - 4 - Question 11

Lens is a portion of a transparent refracting medium bound by two spherical surfaces or one spherical surface and the other plane surface. Lenses are divided into two classes, namely, convex lens or converging lens, and concave lens or diverging lens.

Physics: CUET Mock Test - 4 - Question 12

How much intensity of the image is increased if the diameter of the objective of a telescope is doubled?

Detailed Solution for Physics: CUET Mock Test - 4 - Question 12

On doubling the diameter, the area of the objective increases four times. Its light-gathering power increases four times. The brightness of the image also increases four times. Therefore, the intensity of the image increases by four.

Physics: CUET Mock Test - 4 - Question 13

The wavelength of light coming from a sodium source is 589 nm. What will be its wavelength in the water?

Detailed Solution for Physics: CUET Mock Test - 4 - Question 13

λ = 589 nm, μ = 1.33.
Wavelength in water, λW = λ/μ
λW = 589/1.33
λW = 443 nm.

Physics: CUET Mock Test - 4 - Question 14

In Young’s double-slit experiment, lights of green, yellow, and orange colors are successively used. Write the fringe widths for the three colors in increasing order.

Detailed Solution for Physics: CUET Mock Test - 4 - Question 14

Fringe width is expressed as:
β = Dλ/d.
Since the wavelength are related as shown → λG < λY < λO, we can say that → βG < βY < βO.

Physics: CUET Mock Test - 4 - Question 15

How did de – Broglie modify Bohr’s postulate?

Detailed Solution for Physics: CUET Mock Test - 4 - Question 15

de – Broglie hypothesis did modify Bohr’s second postulate. This postulate of Bohr regarding the quantization of the angular momentum of an electron was further explained by Louis de Broglie. According to de – Broglie, a moving electron in its circular orbit behaves like a particle-wave.

Physics: CUET Mock Test - 4 - Question 16

X is thicker in the middle than at the edges, whereas, Y is thicker at the edges than in the middle. Identify ‘X’ and ‘Y’.

Detailed Solution for Physics: CUET Mock Test - 4 - Question 16

When the lens is thicker in the middle than at the edges, then it is convex lens. When the lens is thicker at the edges than in the middle, then it is concave lens. Therefore, X = convex lens, and Y = concave lens.

Physics: CUET Mock Test - 4 - Question 17

A fly is sitting on the objective of a telescope. What will be its effect on the final image of the distant object?

Detailed Solution for Physics: CUET Mock Test - 4 - Question 17

The fly will not be seen in the final image. But the intensity of the final image gets reduced because light will not enter the telescope from that part of the object where the fly is sitting. Therefore, a reduction effect will be observed in the final image of the fly.

Physics: CUET Mock Test - 4 - Question 18

A light wave enters from air into glass. How will the energy of the wave be affected?

Detailed Solution for Physics: CUET Mock Test - 4 - Question 18

When a light wave enters from the air medium into the glass medium, the energy of the wave decreases because a part of the light wave is reflected in the air. Therefore, in this way, energy will be affected.

Physics: CUET Mock Test - 4 - Question 19

In Young’s double-slit experiment, the two parallel slits are made one millimeter apart and a screen is placed one meter away. What is the fringe separation when blue-green light of wavelength 500 nm is used?

Detailed Solution for Physics: CUET Mock Test - 4 - Question 19

Fringe width is given as:
β = Dλ/d.
So β = (1×500×10−9)/(10−3)
β = 0.5 mm
Therefore, the fringe separation when blue-green light of wavelength 500 nm is used is 0.5 mm.

Physics: CUET Mock Test - 4 - Question 20

Which of the following can be chosen to analogously represent the behavior of a particle?

Detailed Solution for Physics: CUET Mock Test - 4 - Question 20

A string is used to represent the behavior of a particle analogously to the waves traveling on it. Particle waves can lead to standing waves held under resonant conditions. When a stationary string is plucked, it causes several wavelengths to be excited. But, we know that only the ones which have nodes at the ends will survive.

Physics: CUET Mock Test - 4 - Question 21

Identify the material whose resistivity lie between 10-6 Ωm and 104 Ωm.

Detailed Solution for Physics: CUET Mock Test - 4 - Question 21

The resistivities of semiconductors lie between 10-6 Ωm and 104 Ωm. A semiconductor material has an electrical conductivity value falling between that of a conductor, such as metallic aluminum, and an insulator, such as wood. Silicon and germanium are typical semiconductors.

Physics: CUET Mock Test - 4 - Question 22

Two lenses of focal lengths 5 cm and 50 cm are to be used for making a telescope. Which lens will you use for the objective?

Detailed Solution for Physics: CUET Mock Test - 4 - Question 22

In a telescope, the objective should have a large focal length than the eyepiece. So the lens of 50 cm focal length will be used as the objective. So, the smaller one of the two, i.e. the 5 cm focal length lens will be used as the eyepiece.

Physics: CUET Mock Test - 4 - Question 23

If a wave undergoes refraction, what will be the phase change?

Detailed Solution for Physics: CUET Mock Test - 4 - Question 23

When a wave undergoes refraction, the phase change will be zero. The phase change is what guides the process. Therefore, no phase change occurs to a wave during refraction.

Physics: CUET Mock Test - 4 - Question 24

What would be the resultant intensity at a point of destructive interference, if there are two identical coherent waves of intensity I0 producing an interference pattern?

Detailed Solution for Physics: CUET Mock Test - 4 - Question 24

Resultant intensity at the point of destructive interference will be as follows:
I = I0 + I0 + 2√I0 I0 cos 180o
I = 0
Therefore, the value of the resultant intensity at a point of destructive interference is zero.

Physics: CUET Mock Test - 4 - Question 25

A solenoid has core of a material with relative permeability 200 and its windings carry a current of 2 A. The number of turns of the solenoid is 200 per meter. What is the magnetization of the material?

Detailed Solution for Physics: CUET Mock Test - 4 - Question 25

Given: number of turns (n) = 200 turns per meter; current (I) = 2 A; Relative permeability (µr) = 200
Magnetic intensity is given by: H = nI = 200 × 2 = 400 A/m
μr = 1 + γ → γ is the magnetic susceptibility of the material
γ = μr – 1
Magnetization → M = γ x H
M = (μr – 1) × H
M = (200 – 1) × 200
M = 199 × 200
M = 79600
M = 7.96 × 104 A/m ≈ 8 × 104 A/m

Physics: CUET Mock Test - 4 - Question 26

Which of the following is used to increase the range of a telescope?

Detailed Solution for Physics: CUET Mock Test - 4 - Question 26

The light-gathering power of the objective will increase and even faint objects will become visible. This is done by increasing the diameter of the objective. So, by increasing the diameter of the objective, the range of the telescope can be increased.

Physics: CUET Mock Test - 4 - Question 27

When a wave undergoes reflection at a denser medium, what will be the phase change?

Detailed Solution for Physics: CUET Mock Test - 4 - Question 27

When a wave is reflected in the rarer medium from the surface of a denser medium, it undergoes a phase change of π radian. Therefore, when a wave undergoes reflection at a denser medium, the phase change will be π radian.

Physics: CUET Mock Test - 4 - Question 28

What happens to the interference pattern if the phase difference between the two sources varies continuously?

Detailed Solution for Physics: CUET Mock Test - 4 - Question 28

The positions of bright and dark fringes will change rapidly. Such rapid changes cannot be detected by our eyes. Uniform illumination is seen on the screen i.e., the interference pattern disappears.

Physics: CUET Mock Test - 4 - Question 29

How did de – Broglie conclude the modification of Bohr’s II postulate?

Detailed Solution for Physics: CUET Mock Test - 4 - Question 29

de – Broglie concluded his modification of Bohr’s second postulate by stating that the wavelengths of matter waves can be quantized. This implies that the electrons can exist in those orbits which had a complete set of several wavelengths.

Physics: CUET Mock Test - 4 - Question 30

According to the thin lens formula, which one of the following is true regarding the focal length of the lens?

Detailed Solution for Physics: CUET Mock Test - 4 - Question 30

Thin lens formula is given as:
1/f = 1/v - 1/u
Where u = distance of the object from the optical center of the lens; v = distance of the image from the optical center of the lens; f = focal length of a lens. According to the thin lens formula, f is positive for converging or convex lens and f is negative for a diverging or concave lens.

Physics: CUET Mock Test - 4 - Question 31

A rectangular coil, of sides 4 cm and 5 cm respectively, has 50 turns in it. It carries a current of 2 A, and is placed in a uniform magnetic field of 0.5 T in such a manner that its plane makes an angle of 60o with the field direction. Calculate the torque on the loop.

Detailed Solution for Physics: CUET Mock Test - 4 - Question 31

The magnitude of torque experienced by a current carrying coil kept in a uniform magnetic field is given by:
τ = MB sin (θ) = (NIA) × B sin (θ)
M → Magnetic moment of the coil
N → Number of turns
I → Current in coil
A → Area of the coil
θ → Angle between normal to the plane of the coil and the direction of the magnetic field
Given: N = 50; A = 4 × 5 = 20 cm2 = 20 × 10-4 m2; B = 0.5 T; I = 2 A
θ = 90o – 60o = 30o
τ = (NIA) × B sin (θ)
τ = 50 × 2 × 0.5 × 20 × 10-4 × sin (30o)
τ = 0.05
τ = 5 × 10-2 N m

Physics: CUET Mock Test - 4 - Question 32

Which among the following is not attracted by magnets?

Detailed Solution for Physics: CUET Mock Test - 4 - Question 32

A magnet is a material that has both attractive and directive properties. It attracts small pieces of iron, nickel, cobalt, etc. This property of attraction is called magnetism. Going by this criteria, copper is not attracted by magnets.

Physics: CUET Mock Test - 4 - Question 33

Which of the following is not a basic property of magnets.

Detailed Solution for Physics: CUET Mock Test - 4 - Question 33

Attractive property, directive property and the law of magnetic poles are some of the important properties of magnets. So unlike electric charges, magnetic monopoles do not exist. Every magnet exists as a dipole.

Physics: CUET Mock Test - 4 - Question 34

What is the SI unit of power of a lens?

Detailed Solution for Physics: CUET Mock Test - 4 - Question 34

The power of a lens is defined as the reciprocal of its focal length in meters. The expression is given as:
P = 1/f
Where P is the power and f is the focal length in meters. Lens surface power can be found with the index of refraction and the radius of curvature. The SI unit of power of a lens is diopter.

Physics: CUET Mock Test - 4 - Question 35

‘X’ can see objects in the ultra-violet light while human beings cannot do so. Identify X.

Detailed Solution for Physics: CUET Mock Test - 4 - Question 35

Bees have some retinal cones that are sensitive to ultra-violet light, so they can see objects in ultra-violet light. Humans are ultra-violet blind. Therefore, a human being cannot see UV light, whereas bees can.

Physics: CUET Mock Test - 4 - Question 36

A light wave enters from air into glass. How will the frequency of the wave be affected?

Detailed Solution for Physics: CUET Mock Test - 4 - Question 36

The frequency of the wave remains unchanged. This is because the frequency is independent of the wave dynamics. Therefore, when a light wave enters from the air medium into the glass medium, the frequency will be the same.

Physics: CUET Mock Test - 4 - Question 37

What will be the effect on the fringes formed in Young’s double-slit experiment if the apparatus is immersed in water?

Detailed Solution for Physics: CUET Mock Test - 4 - Question 37

The wavelength of light in water (λ’ = (λ/μ)) is less than that in air. When the apparatus is immersed in water, the fringe width decreases. This is the impact experienced by the apparatus when immersed in water.

Physics: CUET Mock Test - 4 - Question 38

How does the magnifying power of a telescope change on increasing the diameter of its objective?

Detailed Solution for Physics: CUET Mock Test - 4 - Question 38

Magnifying power of a telescope is given as:
m = f0/fe
It is independent of the aperture of the object. So the magnifying power is not affected when the diameter of the objective is increased.

Physics: CUET Mock Test - 4 - Question 39

What would be the resultant intensity at a point of constructive interference, if there are two identical coherent waves of intensity I’ producing an interference pattern?

Detailed Solution for Physics: CUET Mock Test - 4 - Question 39

Resultant intensity at the point of constructive interference is given as follows:
I = I’ + I’ + 2√I’I’ cos 0o
I = 4 I‘
Therefore, the value of the resultant intensity at a point of constructive interference is 4 I’.

Physics: CUET Mock Test - 4 - Question 40

Which of the following is a natural magnet?

Detailed Solution for Physics: CUET Mock Test - 4 - Question 40

No, this is a false statement. The power of a convex lens is positive as a convex lens has a positive focal length, while the power of a concave lens is negative as a concave lens has a negative focal length.

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