CBSE 12 Physics Question Paper-2021 Term-2 by Pavan | Practice Test to Test Your Knowledge
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  3. CBSE 12 Physics Question Paper-2021 Term-2
CBSE 12 Physics Question Paper-2021 Term-2

CBSE 12 Physics Question Paper-2021 Term-2

This mock test includes actual CBSE Class 12 Physics board exam questions from the year 2021 Term-2, helping students understand exam trends and practice real paper format

2025-08-12
Pavan Pavan
CBSE Class 12 Physics 2021 Grade 12

Duration

30 min

Questions

30

Marking

Negative

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Questions Preview

In a pure semiconductor crystal of Si, if antimony is added, what type of extrinsic semiconductor is obtained?

A
N-type semiconductor
B
P-type semiconductor
C
Intrinsic semiconductor
D
Both P-type and N-type semiconductors

Is it possible for the electrons in two different hydrogen atoms to have different energies but the same orbital angular momentum according to the Bohr model?

A
Yes, because orbital angular momentum depends on quantum number
B
No, because orbital angular momentum must be the same for the same state
C
Yes, if the atomic numbers are different
D
No, the electron energies are directly tied to angular momentum

What device converts the change in intensity of illumination to a change in electric current?

A
Photodiode
B
Thermistor
C
Phototransistor
D
Photocell

What is the frequency of radiation emitted when a hydrogen atom de-excites from level n to level (n - 1)?

A
1.24 x 10^14 Hz
B
4.56 x 10^14 Hz
C
1.57 x 10^13 Hz
D
1.96 x 10^13 Hz

In a compound microscope, for a magnification of 30X, what is the focal length of the objective lens?

A
1.25 cm
B
5.0 cm
C
10.0 cm
D
0.5 cm

What is the kinetic energy of the fastest electrons emitted when light of wavelength 2000 Å falls on a metal surface with work function 4.2 eV?

A
2.5 eV
B
4.2 eV
C
3.2 eV
D
5.0 eV

What happens to the energy of emitted electrons if the intensity of light with the same wavelength is doubled?

A
Energy of electrons increases
B
Energy of electrons stays the same
C
Energy of electrons decreases
D
Energy depends on frequency, not intensity

What is the new focal length of a convex lens when placed in a medium with refractive index 1.25, if its original focal length in air is 20 cm?

A
16 cm
B
25 cm
C
18 cm
D
22 cm

What is the angular magnification of a telescope with an objective focal length of 140 cm and an eyepiece focal length of 5.0 cm?

A
28X
B
35X
C
25X
D
30X

Which phenomenon is prominently involved in the formation of mirage in deserts?

A
Refraction
B
Reflection
C
Diffraction
D
Scattering

What is the change in the energy of emitted electrons when the intensity of light is doubled, while keeping the wavelength constant?

A
The energy remains the same
B
The energy doubles
C
The energy is halved
D
Energy depends only on frequency, not intensity

In an optical fiber, if n1 and n2 are the refractive indices of the core and cladding, which of the following is true?

A
n1 < n2
B
n1 = n2
C
n1 >> n2
D
n1 > n2

The refractive index of a diamond is greater than that of water. How will the critical angle of diamond-liquid interface compare to the critical angle of diamond-water interface?

A
The critical angle will decrease
B
The critical angle will remain the same
C
The critical angle will increase
D
The critical angle depends on the refractive index of the liquid

Which of the following is the correct expression for the range of angles of incident rays for total internal reflection in a light pipe made of glass (n = 1.68) surrounded by cladding (n = 1.44)?

A
0 < i < 60°
B
0 < i < 45°
C
0 < i < 30°
D
0 < i < 90°

Which of the following e.m. waves is suitable for radar systems used in aircraft navigation?

A
Microwaves
B
Infrared waves
C
Radio waves
D
Ultraviolet waves

Which of the following factors will lead to a decrease in the Earth's average surface temperature if the atmosphere were absent?

A
Decreased greenhouse effect
B
Increased heat absorption
C
Higher sunlight reflection
D
Increased water vapor content

What happens when an e.m. wave exerts pressure on the surface it is incident on?

A
The wave's energy is transferred to the surface
B
The wave is reflected back
C
The surface absorbs all the energy
D
No effect on the surface

What is the purpose of using a pn-junction diode to convert an ac signal to a pulsating dc signal?

A
It allows current to flow only in one direction
B
It amplifies the signal
C
It filters high-frequency components
D
It increases the signal frequency

What is the angular magnification of an astronomical telescope with an objective focal length of 140 cm and an eyepiece focal length of 5.0 cm?

A
28X
B
35X
C
25X
D
30X

What happens when the slits in Young's double slit experiment are identical?

A
Intensity may vary between zero and four times the intensity due to single slit
B
Intensity remains constant
C
Intensity may vary between zero and two times the intensity due to single slit
D
No intensity variation occurs

In diffraction through a single slit, what is the relationship between the intensity and phase angle?

A
Intensity decreases as phase angle increases
B
Intensity increases with phase angle
C
Intensity is independent of phase angle
D
Intensity varies periodically with phase angle

In a hydrogen atom, the frequency of radiation emitted when the atom de-excites from level n to level (n-1) can be compared to which classical frequency?

A
Classical frequency of revolution of an electron
B
Frequency of a photon in the electromagnetic spectrum
C
Frequency of an electron in its ground state
D
Resonance frequency of the atom

What is the energy of the fastest electrons emitted from the surface when light of wavelength 2000 Å falls on a metal surface of work function 4.2 eV?

A
2.5 eV
B
4.2 eV
C
1.2 eV
D
5.0 eV

What is the refractive index of a medium if the focal length of a convex lens in air is 20 cm and in the medium is 16 cm?

A
1.25
B
1.68
C
1.44
D
1.5

Which phenomenon is responsible for the formation of a mirage in the desert?

A
Refraction
B
Total internal reflection
C
Diffraction
D
Reflection

What is the relationship between the wavelength and frequency of light in a vacuum?

A
Frequency and wavelength are inversely proportional
B
Frequency and wavelength are directly proportional
C
Frequency and wavelength have no relation
D
Wavelength is independent of frequency

Which of the following electromagnetic waves has the shortest wavelength?

A
Gamma rays
B
X-rays
C
Ultraviolet rays
D
Radio waves

What happens when a light wave passes from a rarer medium to a denser medium?

A
It bends away from the normal
B
It bends towards the normal
C
There is no bending
D
It gets reflected back

Which of the following is responsible for the production of the rainbow in the sky?

A
Reflection of light
B
Refraction of light
C
Diffraction of light
D
Dispersion of light

What is the main characteristic of the emission spectrum of hydrogen?

A
It consists of discrete lines corresponding to specific energies
B
It is continuous
C
It is identical to the absorption spectrum
D
It produces a single line