Q: During an adiabatic process, the pressure P and volume V of an ideal gas are related by:

PV^\gamma = \text{const}. Standard adiabatic state equation: P V^\gamma = \text{constant}

Q: Two tuning forks of frequencies 256\text{ Hz} and 260\text{ Hz} are sounded together. The number of beats heard per second is:

4. Beat frequency f_b = |f_1 - f_2| = |260 - 256| = 4\text{ s}^{-1}

Q: An electric dipole of moment \vec{p} placed in a uniform electric field \vec{E} experiences a torque equal to:

\vec{p} \times \vec{E}. \vec{\tau} = \vec{p} \times \vec{E}

Q: The magnetic flux linked with a coil changes from 0.8\text{ Wb} to 0.2\text{ Wb} in 0.1\text{ s}. The magnitude of induced EMF is:

6\text{ V}. |e| = |\Delta\Phi/\Delta t| = \frac{0.8 - 0.2}{0.1} = 6\text{ V}

Q: In a purely inductive alternating current circuit, current lags alternating voltage by a phase angle of:

\pi/2\text{ rad}. Pure inductor: current lags EMF by pi/2 radians (90 degrees)

Question 1

During an adiabatic process, the pressure P and volume V of an ideal gas are related by:

Accepted Answer

PV^\gamma = 	ext{const}. Standard adiabatic state equation: P V^\gamma = 	ext{constant}

Question 2

Two tuning forks of frequencies 256	ext{ Hz} and 260	ext{ Hz} are sounded together. The number of beats heard per second is:

Accepted Answer

4. Beat frequency f_b = |f_1 - f_2| = |260 - 256| = 4	ext{ s}^{-1}

Question 3

An electric dipole of moment \vec{p} placed in a uniform electric field \vec{E} experiences a torque equal to:

Accepted Answer

\vec{p} 	imes \vec{E}. \vec{	au} = \vec{p} 	imes \vec{E}

Question 4

The magnetic flux linked with a coil changes from 0.8	ext{ Wb} to 0.2	ext{ Wb} in 0.1	ext{ s}. The magnitude of induced EMF is:

Accepted Answer

6	ext{ V}. |e| = |\Delta\Phi/\Delta t| = \frac{0.8 - 0.2}{0.1} = 6	ext{ V}

Question 5

The self-inductance of a long solenoid having N turns is directly proportional to:

Accepted Answer

N^2. L = \frac{\mu_0 N^2 A}{l} \implies L \propto N^2

Question 6

In a purely inductive alternating current circuit, current lags alternating voltage by a phase angle of:

Accepted Answer

\pi/2	ext{ rad}. Pure inductor: current lags EMF by pi/2 radians (90 degrees)

Question 7

The radius of the first Bohr orbit of a hydrogen atom is r_0. The radius of the third Bohr orbit is:

Accepted Answer

9r_0. r_n \propto n^2 \implies r_3 = 3^2 r_0 = 9r_0

Question 8

The half-life of a radioactive substance is 4	ext{ hours}. What fraction of original activity remains after 16	ext{ hours}?

Accepted Answer

1/16. n = 16/4 = 4 half-lives. N/N_0 = (1/2)^4 = 1/16

Question 9

A Zener diode is primarily designed to operate in which region of its characteristic curve?

Accepted Answer

Reverse breakdown region. Zener diodes act as voltage regulators in the reverse breakdown regime

Question 10

Which logic gate produces output 0 only when both of its inputs are 1?

Accepted Answer

NAND. NAND: Y = \overline{A \cdot B}. Output is 0 only when A=1, B=1

Question 11

A capacitor of 20\mu	ext{F} is charged to 500	ext{ V}. The energy stored inside this capacitor is:

Accepted Answer

2.5	ext{ J}. U = \frac{1}{2}CV^2 = \frac{1}{2}(20 	imes 10^{-6})(500^2) = 2.5	ext{ J}

Question 12

A planar current loop of area A carries steady current I. Its magnetic dipole moment is:

Accepted Answer

IA. Dipole moment M = I \cdot A

Question 13

Two vectors A = 2i + 3j and B = 3i - 2j are:

Accepted Answer

Perpendicular to each other. A dot B = (2)(3) + (3)(-2) = 0 implies mutually perpendicular

Question 14

A projectile launched with speed u at an angle theta achieves maximum horizontal range when theta is:

Accepted Answer

45 degrees. R = \frac{u^2 \sin 2	heta}{g}. Maximum when \sin 2	heta = 1 \implies 	heta = 45 degrees

Question 15

A constant force of 20	ext{ N} acts on a mass of 5	ext{ kg} for 2	ext{ seconds}. The change in linear momentum is:

Accepted Answer

40	ext{ kg}\cdot	ext{m/s}. \Delta p = F \cdot \Delta t = 20 	imes 2 = 40	ext{ kg}\cdot	ext{m/s}

Question 16

If the distance between two point masses is doubled, the gravitational force between them will:

Accepted Answer

Reduce to 1/4th. F \propto 1/r^2 \implies F' = F/2^2 = F/4

Question 17

At what temperature do the Celsius and Fahrenheit temperature scales give the exact same numerical value?

Accepted Answer

−40 degrees. \frac{C}{5} = \frac{F-32}{9} \implies 9x = 5x - 160 \implies x = -40 degrees

Question 18

The apparent change in pitch or frequency of sound due to relative motion between source and observer is called:

Accepted Answer

Doppler effect. Doppler effect describes apparent pitch shifts due to relative velocity

Question 19

Eight equal spherical water droplets each of radius r coalesce into a single big droplet. The surface energy of the system will:

Accepted Answer

Decrease by 50%. Volume conservation gives R = 2r. U_i = 8(4\pi r^2 T) = 32\pi r^2 T; U_f = 4\pi R^2 T = 16\pi r^2 T. Energy decreases by 50%

Question 20

A solid cylinder rolls down an inclined plane of inclination theta without slipping. Its linear acceleration is:

Accepted Answer

\frac{2}{3}g\sin	heta. a = \frac{g\sin	heta}{1 + k^2/R^2} = \frac{g\sin	heta}{1 + 1/2} = \frac{2}{3}g\sin	heta

Physics — MH-CET Full Length Paper MCQs with Solutions

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