Physics | NEET Entrance Exam | Under Graduate Entrance Exams Online Objective Test

Under Graduate Entrance Exams NEET Entrance Exam # Physics Units and Measurements Prepare / Learn

Q1. One mole of an ideal gas at standard temperature and pressure occupies 22.4 L (molar volume). What is the ratio of molar volume to the atomic volume of a mole of hydrogen? (Take the size of hydrogen molecule to be about 1 Å).

A. ≅105

≅103

C. ≅102

D. ≅104

Answer : Option D
Explaination / Solution:

Radius of hydrogen atom, r = 0.5 = 0.5 × 10–10 m
Volume of hydrogen atom = $\frac{4}{3} \times \frac{22}{7} \times (0.5 \times 10^{- 10})^{3}$

= $0.524 \times 10^{- 30} m^{3}$

Now, 1 mole of hydrogen contains 6.023 × 1023 hydrogen atoms.
Volume of 1 mole of hydrogen atoms, Va = 6.023 × 1023 × 0.524 × 10–30
= 3.16 × 10–7 m3
Molar volume of 1 mole of hydrogen atoms at STP,
Vm = 22.4 L = 22.4 × 10–3 m3

=> $\frac{V_{m}}{V_{a}} = \frac{22.4 \times 10^{- 3}}{3.16 \times 10^{- 7}}$ = 7.08 $\times 10^{- 4}$

= $≅ 10^{- 4}$

Under Graduate Entrance Exams NEET Entrance Exam # Physics Oscillations Prepare / Learn

Q2. A particle is oscillating according to the equation X=7 cos 0.5 πt, where t is in seconds. The point moves from the position of equilibrium to maximum displacement in time

A. 0.5 seconds

B. 2.0 seconds

C. 1.0 seconds

D. 4.0 seconds

Answer : Option B
Explaination / Solution:
No Explaination.

Under Graduate Entrance Exams NEET Entrance Exam # Physics Magnetism and Matter Prepare / Learn

Q3. A closely wound solenoid of 2000 turns and area of cross-section

1.6 \times 1 0^{- 4} m^{2}

, carrying a current of 4.0 A, is suspended through its centre allowing it to turn in a horizontal plane. If a uniform horizontal magnetic field of

7.5 \times 10 - 2

T is set up at an angle of

30

with the axis of the solenoid,force and torque on the solenoid are

A. 0.0N,0.048 Nm

B. 0.0N,0.058 Nm

C. 0.5N,0.068 Nm

D. 0.5N,0.078 Nm

Answer : Option A
Explaination / Solution:
No Explaination.

Under Graduate Entrance Exams NEET Entrance Exam # Physics Wave Optics Prepare / Learn

Q4. In Young’s double-slit experiment using monochromatic light of wavelength l, the intensity of light at a point on the screen where path difference is λ, is K units. What is the intensity of light at a point where path difference is λ /3?

A. K

B. K/4

C. K/2

D. K/8

Answer : Option B
Explaination / Solution:
No Explaination.

Under Graduate Entrance Exams NEET Entrance Exam # Physics Moving Charges and Magnetism Prepare / Learn

Q5. A steel wire of length l has a magnetic moment M. It is then bent into a semicircular arc. The new magnetic moment is

A. M / l

B. M

C. M×l

D. 2M/π

Answer : Option D
Explaination / Solution:

If the steel wire is assumed to be a bar magnet of length l and pole strength qm, its magnetic moment

M = q_{m} l

When it is bent into a semicircular arc of radius r, the distance between the poles is equal to its diameter

l^{'} = 2 r

The new magnetic moment

M^{'} = q_{m} l^{'} = q_{m} (2 r)

.Since,

l = π r

\frac{M^{'}}{M} = \frac{q_{m} (2 r)}{q_{m} l} = \frac{2 r}{l} = \frac{2 r}{π r} = \frac{2}{π}

M^{'} = \frac{2 M}{π}

Under Graduate Entrance Exams NEET Entrance Exam # Physics Electronic Devices Prepare / Learn

Q6. To use a transistor as an amplifier

A. both junctions are reverse biased

B. no biasing voltage is required

C. the emitter- base junction is forward biased and the base – collector junction is reverse biased

D. both junctions are forward biased

Answer : Option C
Explaination / Solution:

Amplifier is an electronic device. The device which increases the value of a signal is called amplifier. In input a weak signal is applied, in output a strong, same shape signal is gained. Amplify means to increase the value of something.

The collector is reverse biased and the emitter is forward biased while using transistor as an amplifier.

Under Graduate Entrance Exams NEET Entrance Exam # Physics Motion in A Straight Line Prepare / Learn

Q7.

A stone thrown from the top of a building is given an initial velocity of 20.0 m/s straight upward. Determine the velocity in m/sec when the stone returns to the height from which it was thrown. g =9.8 m / $s e c^{2}$

s e c^{2}

A. -15.0

B. -25.0

C. -30.0

D. -20.0

Answer : Option D
Explaination / Solution:

$(v_{C})^{2} - (v_{A})^{2} = 2 a (y_{C} - y_{A})$

$W i t h y_{C} = y_{A}$

$(v_{C})^{2} = (v_{A})^{2} ⟹ v_{C} = \pm v_{A}$

As the motion of the stone is downward, and the”+”sign was assigned for the upward motion,

we get for vC = −vA= −20 m/s.

Under Graduate Entrance Exams NEET Entrance Exam # Physics Waves Prepare / Learn

Q8. Longitudinal waves cannot be propagated through

A. vacuum

B. a solid

C. a gas

D. a liquid

Answer : Option A
Explaination / Solution:
No Explaination.

Under Graduate Entrance Exams NEET Entrance Exam # Physics Electromagnetic Induction Prepare / Learn

Q9. Assume that a motor in which the coils have a total resistance of 10Ω is supplied by a voltage of 120 V. When the motor is running at its maximum speed, the back emf is 70 V. Current in the coils when the motor is turned on and when it has reached maximum speed are

A. 14 A,5 A

B. 12 A,5 A

C. 16 A,5 At

D. 12 A,4 A

Answer : Option B
Explaination / Solution:

when motor is turned on

$i = \frac{V}{R} = \frac{120}{10} = 12 A$

when it has reached maximum speed, the back emf is 70 V then current will be

$i = \frac{V}{R} = \frac{120 - 70}{10} = 5 A$

Under Graduate Entrance Exams NEET Entrance Exam # Physics Electromagnetic Waves Prepare / Learn

Q10. It is necessary to use satellites for long distance TV transmission because

A. Television signals are absorbed by ionosphere

B. Television signals are attenuated by ionosphere

C. Satellites transmit the signals all over the earth

D. Television signals are not properly reflected by the ionosphere. Therefore, reflection is effected by satellites.

Answer : Option D
Explaination / Solution:
No Explaination.

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