# PHYSICS MCQs

Heat is the form of:
a) Power
b) Work
c) Energy
d) Motion

Pressure of the gas depends upon:
a) Only on molecular speed
b) Only on mass of molecule
c) Only on number of molecules in a unit volume
d) Number of molecules in a unit volume, mass and speed of molecule

In the isothermal process, one of the
following is constant:
a) Pressure
b) Volume
c) Temperature
d) Heat energy
e) Specific heat

A process in which no heat enters or leaves
the system is called:
a) Isothermal process
c) Isochoric process
d) Isobaric process

For a gas obeying Boyle’s law, if the
pressure is doubled, the volume becomes:
a) Double
b) One half
c) Four times
d) One fourth

Gas law PV γ = constant is for:
a) Isothermal process
c) Isobaric process
d) Isochoric process

Cloud formation in the atmosphere is
example of:
b) Isothermal process
c) Isochoric process
d) Isobaric process

Boyle’s law holds for ideal gases in.
a) Isochoric processes
b) Isobaric processes
c) Isothermal processes

Which one is true for internal energy?
a) It is sum of all forms of energies
associated with molecules of a system.
b) It is a state function of a system
c) It is proportional to transnational K.E of the molecules
d) All are correct

The internal energy of an ideal gas is
directly proportional to:
a) Potential energy
b) Translational kinetic energy
c) Vibrational kinetic energy
d) None of these

Which one is correct relation?
a) CP + CV = γ
b) CP = 1 + R/CV
c) γ = CP/CV
d) CP = 1 − R/CV

Specific heats of a gas at constant pressure
and at constant volume are respectively Cp
and Cv :
a) Cp < Cv
b) Cp > Cv
c) Cp = Cv
d) none of these

Numerical value of Boltzmann’s constant is.
a) 1.38 × 10−31JK−1
b) 3.18 × 10−31JK−1
c) 3.18 × 10−23 JK −1
d) 1.38 × 10−23 JK −1

The first law of thermodynamics is an
expression of:
a) The conservation of energy
b) Conservation of mass
c) Heat death of the universe

The amount of heat required raising the
temperature of 1 kg of a substance through
1 K is called
a) Specific heat
b) Heat capacity
c) Calorie
d) Joule

The expression for isothermal process is:
a) Q = U
b) Q = W
c) U = W
d) U = −W

In adiabatic expansion, first law of
thermodynamics becomes:
a) ∆Q = ∆W
b) ∆Q = ∆U
c) ∆W = ∆U
d) None of these

The Celsius scale starts from:
a) 32°F
b) 273 K
c) 0°C
d) 373 K

Unit of thermodynamic scale of
temperature is:
a) Kelvin
c) Fahrenheit
d) Celsius

Normal human body temperature 98.6o F corresponds to.
a) 37oC
b) 42 oC
c) 55 oC
d) 410 oC

Triple point of water is.
a) 373.16 K
b) 284.16 K
c) 300.16 K
d) 273.16 K

If the temperature of the sink is decreased,
the efficiency of Carnot engine:
a) Decreases
b) Increases
c) Remains the same
d) First increases and then decreases

The area enclosed by the curve ABCDA for
a Carnot heat engine represents the work
done by Carnot engine.
a) At any instant
b) Averagely
c) During its operation
d) During one cycle

Carnot cycle is:
a) Reversible
b) Irreversible
c) Both
d) None of these

The efficiency of diesel engine is about:
a) 50% to 60%
b) 25% to 30%
c) 35% to 40%
d) 40% to 50%

The efficiency of petrol engine is about:
a) 30% to 35%
b) 25% to 30%
c) 35% to 40%
d) None of these

The efficiency of a Carnot engine between
HTR at T1 and LTR at T2 is given by:
a)211TT-
b)12 1TT -T
c)11 2TT -T
d)1 21T T-T

Working cycle of a typical petrol engine
consists of:
a) Two strokes
b) Four strokes
c) Six strokes
d) Eight strokes

The unit of entropy is:
a) JK
b) K/j
c) J/K
d) J/K2

Mathematically, entropy is represented by:
a) ∆Q =∆S/T
b) ∆S =∆Q/T
c) ∆S = ∆Q/T
d) ∆S =∆T/Q

The increase in the entropy means the
increase in:
a) Disorder
b) Unavailability of energy
c) Randomness
d) All of these

The property of a system that remains
constant during an adiabatic process is
called:
a) Internal energy
b) Entropy
c) Temperature
d) Pressure

In which process entropy remains constant.
a) Isobaric
b) Isochoric
d) Isothermal

When heat is added to the system, the
entropy change is:
a) Positive
b) Negative
c) Zero
d) None

A lens which converges a beam of parallel rays to a point is called
(a) Diverging (or concave) lens
(b) Converging (or convex) lens
(c) Plano concave lens
(d) Plano convex lens

A point where the incident parallel rays of light converge or appear to diverge after passing through a lens is called
(a) Center of curvature
(b) Focus
(c) Optical centre
(d) Aperture

The diameter of a lens is called
(a) Focal length
(b) Principal axis
(c) Aperture

In going form a denser to rarer medium a array of light is
(a) undeviated
(b) bent away form the normal
(c) bent towards the normal
(d) polarized

Unit of power of a lens is
(a) Meter
(b) watt
(c) dioptre
(d) horsepower

Dioptre power of an concave lens of 10 cm focal length is
(a) 10 dioptre
(b) -10 dioptre
(c) 1/10 dioptre
(d) -1/10 dioptre

The power of a concave lens is
(a) real
(b) virtual
(c) positive
(d) negative

The minimum distance between an object and its real image in a convex lens is
a. 2 f
b. 2.5 f
c. 3 f
d. 4f

If an object is placed away form ‘2f’ of a converging lens, then the image will be
a. Real and erect
b. Virtual and erect
c. Real and inverted
d. Virtual

A convex lens gives a virtual image only when the objects leis
a. Between principal focus and center of curvature
b. Beyond 2 f
c. At the principal focus
d. Between principal focus and optical center

Magnifying power of simple microscope
a. Increase with increase in focal length
b. Increase with decrease in focal length
c. No effect with decrease or increase with focal length
d. List distance of distinct vision

Image of an object 5 mm high is only 1 cm high. Magnification produced by lens is
a. 0.5
b. 0.2
c. 1
d. 2

The least distance of distinct vision for a normal eye is
a. 15cm
b. 25cm
c. 30cm
d. 40cm

least distance of distinct vision
a. increases with increase in age
b. decrease with increaser in age
c. neither increases nor decreases
d. becomes infinite after 60 years

If a convex lens of large aperture fails to converge the light rays incident on it to a single point, it is said to
suffer form
a. Chromatic aberration
b. Spherical aberration
c. Both spherical and chromatic
d. Distortion

Two convex lenses of equal focal length ‘f’ are placed in contact, the resultant focal length of the
combination is
a. Zero
b. f
c. 2f
d. f/2

A convex lens of focal length ‘f1’and a concave lens of focal length ‘f2’ are placed in contact. The focal
length of the combination is
a. f2 + f1
b. f2 – f1
c. f1f2/f2+f1
d. f1f2/f1-f2

Final image produced by a compound microscope is
a. Real and inverted
b. Real and erect
c. Virtual and erect
d. Virtual and inverted.

for normal adjustment, length of astronomical telescope is
a. fo + fe
b. fo – fe
c. fo/fe
d. fe/fo

In multimode step index fibre the refractive index of core and cladding is
a. Same
b. Different
c. Zero
d. Different with refractive index of core higher than cladding

Dispersional effect may produced error in light signals. This type of error is minimum in.
a. Single mode step index fibre
b. Multimode step index fibre
d. Monomode step index fibre

Light signals passes through multimode graded fibre due to .
a. Continuous refraction
b. Total internal reflection
c. Both continuous refraction and total internal reflection
d. Diffraction

Which one type of fibre is more suitable for transmission of signals in which white light is used?
a. Mono mode step index fibre
b. Multi mode step index fibre
c. Multi mode graded index fibre
d. Single mode step index fibre

Critical angle is that incident angle in denser medium for which angle of refraction is.
a. 0
b. 45
c. 90
d. 180

There is no noticeable boundary between core and cladding.
a. Multi mode step index fibre
b. Multi mode graded index fibre
c. Single mode step index fibre
d. All types of fibre

The electrical signals change into light signals for transmission through optical fibre. A light pulse
represent.
a. Zero (0)
b. One (1)
c. Both zero (0) and one (1)
d. Neither zero (0) nor one (1)

A lens, which is thicker at the center and thicker at the edges, is called.
a. Concave lens
b. Convex lens
c. Plano convex lens
d. Plano concave lens

A spectrometer is used to find.
a. Wave length of light
b. Refractive index of the prism
c. Wavelength of different colours
d. None

If a convex lens of focal length ‘f’ is cut into two identical halves along the lens diameter, the focal length
of each half is.
a. f
b. f/2
c. 2f
d. 3f/2

A convex and concave lens of focal length ‘f’ are in contact, the focal length of the combination will be.
a. Zero
b. f/2
c. 2f
d. Infinite

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