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

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

Q1. Relation between ray and wave front is

A. Rays are parallel to wave front

B. Rays are at acute angle to wave front

C. Rays are tangential to wave front

D. Rays are perpendicular to wave front

Answer : Option D
Explaination / Solution:

Huygens’ construction tells us that the new wavefront is the forward envelope of the secondary waves. When the speed of light is independent of direction, the secondary waves are spherical. The rays are then perpendicular to the wavefronts.

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

Q2. magnetic potential energy Um of Compass needle of known magnetic moment m in a uniform magnetic field field is

A. 2m⃗ .B⃗

B. m⃗ .B⃗

C. 2πm⃗ .B⃗

D. - m⃗ .B⃗

Answer : Option D
Explaination / Solution:
No Explaination.

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

Q3.

The gravitational force on point mass m1 due to point mass m2, m3 & m4 is:

A. the difference of gravitational forces exerted by

m_{2}

m_{3}

and

m_{4}

B. the scalar sum of the gravitational forces exerted by

m_{2}

m_{3}

and

m_{4}

C. the difference of gravitational forces exerted by

m_{4}

m_{3}

and

m_{2}

D. the vector sum of the gravitational forces exerted by

m_{2}

m_{3}

and

m_{4}

Answer : Option D
Explaination / Solution:

According to properties of gravitational force: force between the particles is independent of the presence or absence of other particles; so the principle of superposition is valid i.e. force on a particle due to a number of particles is the resultant of forces due to individual particles i.e.

\vec{F_{1}} + \vec{F_{2}} + \vec{F_{3}} + . . . . . . . . .

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

Q4. The total current in a semiconductor is

A. hole current only

B. the sum of electron and hole currents

C. the difference of electron and hole currents

D. electron current only

Answer : Option B
Explaination / Solution:

Electrons will experience a attractive force from the positive terminal, so they move towards the positive terminal of the battery by carrying the electric current.

Similarly holes will experience a attractive force from the negative terminal, so they moves towards the negative terminal of the battery by carrying the electric current.

Thus, in a semiconductor electric current is carried by both electrons and holes. In intrinsic semiconductor the number of free electrons in conduction band is equal to the number of holes in valence band.

The current caused by electrons and holes is equal in magnitude. The total current in intrinsic semiconductor is the sum of hole and electron current.

Total current = Electron current + Hole current I = $I_{h o l e} + I_{e l e c t r o n}$

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

Q5. Displacement is a

A. Vector

B. tensor

C. Hector

D. scalar

Answer : Option A
Explaination / Solution:

Displacement vector is a vector which gives the position of a point with reference to a point other than the origin of the coordinate system.

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

Q6. Plane electromagnetic waves are

A. Standing waves

B. longitudinal waves

C. transverse waves

D. Shock waves

Answer : Option B
Explaination / Solution:
No Explaination.

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

Q7. Travelling or progressive wave

A. does not move from one point of the medium to all others

B. does not move from one point of the medium to another

C. travels from one point of the medium to another

D. does not move from one point of the medium to any other

Answer : Option C
Explaination / Solution:

As progressive wave means a wave propagating in some onward direction in the medium

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

Q8. Coils

C_{1}

and

C_{2}

are stationary.

C_{1}

connected in series with one very small diwali bulb while

C_{2}

is connected to a battery .If the connection is suddenly snapped

A. the bulb absorbs light

B. nothing happens to the bulb

C. the bulb keeps glowing

D. the bulb glows momentarily.

Answer : Option D
Explaination / Solution:

Flux will be changed due to this current is induced momentarily

Under Graduate Entrance Exams NEET Entrance Exam # Physics Dual Nature of Radiation and Matter Prepare / Learn

Q9. For a given frequency of light and a positive plate potential in the set up below, If the intensity of light is increased then

A. current is unaffected by more intensity

B. current is less with more intensity

C. current is more with more intensity

D. current is inversely proportional to intensity

Answer : Option C
Explaination / Solution:

With increase in intensity no. of photon incident increases. So that more electron emitted from metal and photo current increases with increase in intensity.

Under Graduate Entrance Exams NEET Entrance Exam # Physics System of Particles and Rotational Motion Prepare / Learn

Q10. The vector product of two vectors a and b is a vector c such that the magnitude of c is given by

| a | | b |

tan

θ

| a | | b |

cot

θ

| a | | b |

cos

θ

| a | | b |

θ

Answer : Option D
Explaination / Solution:

As per definition of vector product :-

$\vec{c} = \vec{a} \times \vec{b} = | \vec{a} | | \vec{b} | \sin θ \hat{n}$

$| \vec{c} | = | \vec{a} | | \vec{b} | \sin θ$

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