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

Under Graduate Entrance Exams NEET Entrance Exam # Physics Ray Optics and Optical Instruments Prepare / Learn

Q1. A lens forms a sharp image on a screen. On inserting a parallel sided glass slab between the lens and the screen, it is found necessary to move the screen a distance d away from the lens in order to focus the image sharply. If the refractive index of glass relative to air is μ, the thickness of the glass slab is given by

μ

B. d /

μ

C. d1-1μ

D. d1+1μ

Answer : Option C
Explaination / Solution:
No Explaination.

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

Q2. Half life of a substance is 20 minutes. What is the time between 33

%

decay and 67

%

decay?

A. 25 minutes

B. 40 minutes

C. 20 minutes

D. 30 minutes

Answer : Option C
Explaination / Solution:
No Explaination.

Under Graduate Entrance Exams NEET Entrance Exam # Physics Thermal Properties of Matter Prepare / Learn

Q3. An ideal gas occupies a volume of 100

c m^{3}

2 0^{\circ}

C and 100 Pa. Find the number of moles of gas in the container.

A. 4.30

\times

1 0^{- 6}

B. 4.80

\times

1 0^{- 6}

C. 4.10×10−6

D. 4.60

\times

1 0^{- 6}

Answer : Option C
Explaination / Solution:

number of moles according to gas equation

$n = \frac{P V}{R T} = \frac{100 \times 100 \times 10^{- 6}}{8.31 \times 293} = 4.10 \times 10^{- 6}$

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

Q4. A book with many printing errors contains four different formulas for the displacement y of a particle undergoing a certain periodic motion. Choose the correct formula

A. y = a sin 2

π

B. y = (a/T) sin t/a

C. y = a sin vt

D. y = a sin

s i n \frac{2 π t}{T}

s i n \frac{2 π t}{T}

Answer : Option D
Explaination / Solution:

Dimension of y = M0 L1 T0

Dimension of a = M0L1T0

Dimension of $s i n \frac{2 π t}{T}$ = $M^{0} L^{0} T^{0}$

Dimension of L.H.S = Dimension of R.H.S Hence, the given formula is dimensionally correct.

Under Graduate Entrance Exams NEET Entrance Exam # Physics Alternating Current Prepare / Learn

Q5. A coil has a resistance of 48.0

Ω

. At a frequency of 80.0 Hz the voltage across the coil leads the current in it by

53^{\circ}

. Inductance of the coil is

A. 0.94 H

B. 0.114 H

C. 0.124 H

D. 0.84 H

Answer : Option C
Explaination / Solution:

$\begin{aligned} R = 48 Ω \\ f = 80 H z \\ ϕ = 53^{\circ} \\ ω = 2 π f = 2 \times 3.14 \times 80 \end{aligned}$

in series LR circuit

tanϕ=ωLR

tan53∘=2×3.14×80×L48

43=2×3.14×80×L48

L=0.124H

$\begin{aligned} \tan ϕ = \frac{ω L}{R} \\ \tan 53^{\circ} = \frac{2 \times 3.14 \times 80 \times L}{48} \\ \frac{4}{3} = \frac{2 \times 3.14 \times 80 \times L}{48} \\ L = 0.124 H \end{aligned}$

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

Q6. A ball of mass 50 gm is suspended by a spring with a force constant K=49 N/m. The ball is raised to the position at which the spring is not tensioned and is released without a push. The ball will fall through a maximum distance of

A. 0.04 m

B. 0.02 m

C. 0.03 m

D. 0.01 m

Answer : Option D
Explaination / Solution:
No Explaination.

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

Q7. A bar magnet of magnetic moment 1.5 J/T lies parallel to the direction of a uniform magnetic field of 0.22 T. What is the torque acting on it?

A. 0.0J

B. 0.3J

C. -0.3J

D. 0.23J

Answer : Option D
Explaination / Solution:
No Explaination.

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

Q8. The refractive index of glass is 1.5 which of the two colors red and violet travels slower in a glass prism?

A. violet component of white light travels slower than the red component

B. both red and violet travel faster at the same speed

C. both red and violet travel slower at the same speed

D. red component of white light travels slower than the violet component

Answer : Option A
Explaination / Solution:

The refractive index and wavelength are inversly related. The wavelength of violet is least in the visible region so it bends the most.

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

Q9. A wire is perpendicular to the plane of the paper. A ring of compass needles surrounds the wire in the plane of the paper with center of ring being the center of the wire .Initially there is no current in the wire. What happens after a steady dc current is established in the wire?

A. The needles become parallel to each other

B. The needles become tangential to the ring of which they are a part

C. some needles become parallel to each other while others are uneffected

D. nothing happens

Answer : Option B
Explaination / Solution:

The current carrying wire has a magnetic field around it and the lines of force are in the form of concentric circles with their centers on the wire.

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

Q10. In P-N- P transistor operating as an amplifier with common emitter configurations a change in base current from

100 μ A

200 μ A

produces a change in collector current from 10 mA to 18 mA. The current gain of transistor is

A. 12.5

\times 1 0^{- 3}

B. 25.0

\times 1 0^{- 3}

Answer : Option D
Explaination / Solution:

Current gain of transistor

$β = \frac{△ I_{c}}{△ I_{b}} = \frac{(18 - 10) \times 10^{- 3} A}{(200 - 100) 10^{- 6} A} = \frac{8 \times 10^{- 3}}{100 \times 10^{- 6}} \frac{8 \times 10^{- 3}}{10^{- 4}} = 80$

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