Physics - Online Test

Q1. Two identical point charges of magnitude –q are fixed as shown in the figure below. A third charge +q is placed midway between the two charges at the point P. Suppose this charge +q is displaced a small distance from the point P in the directions indicated by the arrows, in which direction(s) will +q be stable with respect to the displacement?

Answer : Option B
Explaination / Solution:

Hint: Since V=0 along equatorial line
Q2. The wavelength λe of an electron and λp of a photon of same energy E are related by
Answer : Option D
Explaination / Solution:

de Broglie wavelength for an electron

λe= h / √(2mE) ;

λe 1/√E ;

λe2 1/E  ------------- (1)

For photon

λp= hc / E ;

λp 1/E  ------------- (2)

From equation (1) and (2), we have So,

 λp λe2


Q3. Rigid body is a body which
Answer : Option C
Explaination / Solution:

A rigid body is an idealization of a solid body in which deformation or change in shape is neglected on application of deforming force.

Q4. electromagnetic induction i.e currents can be induced in coils (Select the best)
Answer : Option C
Explaination / Solution:

for electromagnetic induction magnet and coil both may move but relative motion between must be present

Q5. work function of a metal is the
Answer : Option B
Explaination / Solution:

When the light strikes on a metal surface, electrons on the surface of the metal get energy from the light and get emitted from the surface. There will be no photoemission from a metal surface below a certain frequency of light. For photoemission minimum frequency of incident light is required. This minimum energy of an electron is called work function.

Q6. Physics is a
Answer : Option C
Explaination / Solution:

The natural sciences seek to understand how the world and universe around us works. There are five major branches (top left to bottom right): Chemistry, astronomy, earth science, physics, and biology.

Q7. A student tunes his guitar by striking a 120 Hertz with a tuning fork, and simultaneously plays the 4th string on his guitar. By keen observation, he hears the amplitude of the combined sound oscillating thrice per second. Which of the following frequencies is the most likely the frequency of the 4th string on his guitar?.
Answer : Option B
Explaination / Solution:
No Explaination.


Q8. The following graph shows current versus voltage values of some unknown conductor. What is the resistance of this conductor?

Answer : Option A
Explaination / Solution:


Q9. The scalar product of two vectors A and B is
Answer : Option C
Explaination / Solution:

Scalar product means dot product and dot product of 2 vectors gives a scalar , example dot product of force and displacement gives work which is scalar

Q10. Suppose an alpha particle accelerated by a potential of V volt is allowed to collide with a nucleus whose atomic number is Z, then the distance of closest approach of alpha particle to the nucleus is
Answer : Option A
Explaination / Solution:


When alpha particle is accelerated at the potential V;

K.E = 2eV