Modern Physics CDS Questions

CDS Physics

Modern Physics MCQ Questions


13.
What is the SI unit of Planck’s constant?
A.
Joule-second
B.
Electronvolt
C.
Newton-meter
D.
Joule
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ANSWER :
A. Joule-second
14.
Which of the following represents Einstein’s mass-energy equivalence?
A.
E = hf
B.
E = mc2
C.
E = kT
D.
E = 1/2mv2
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ANSWER :
B. E = mc2
15.

The charge of an electron is approximately:

A.

1.6 x 10-19 C

B.

1.6 x 10-15 C

C.

1.6 x 10-17 C

D.

1.6 x 10-21 C

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ANSWER :

A. 1.6 x 10-19 C

16.
The nucleus of an atom contains:
A.
Protons and electrons
B.
Neutrons and electrons
C.
Protons and neutrons
D.
Protons, neutrons, and electrons
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ANSWER :
C. Protons and neutrons
17.
X-rays are produced when:
A.
Electrons are accelerated in a vacuum
B.
Electrons are decelerated rapidly by a metal target
C.
Protons collide with a nucleus
D.
Neutrons decay into protons
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ANSWER :
B. Electrons are decelerated rapidly by a metal target
18.

The rest mass energy of an electron is approximately:

A.

9.11 x 10-31 kg

B.

8.2 x 10-14 J

C.

0.511 MeV

D.

1.6 x 10-19 J

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ANSWER :

C. 0.511 MeV