A coil having an area 
is placed in a magnetic field which changes from 
to 
in a time interval t. The e.m.f. induced in the coil will be
|
(a) |
(b) |
(c) 
|
(d) 
|
(a) 
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A copper ring is held horizontally and a bar magnet is dropped through the ring with its length along the axis of the ring. The acceleration of the falling magnet while it is passing through the ring is
|
(a) Equal to that due to gravity |
|
(b) Less than that due to gravity |
|
(c) More than that due to gravity |
|
(d) Depends on the diameter of the ring and the length of the magnet |
The impurity atoms which are mixed with pure silicon to make a P-type semiconductor are those of
|
(a) Phosphorus |
(b) Boron |
(c) Antimony |
(d) Copper |
Assertion : The colour of the green flower seen through red glass appears to be dark.
Reason : Red glass transmits only red light.
|
(a) If both assertion and reason are true and the reason is the correct explanation of the assertion. |
|
(b) If both assertion and reason are true but reason is not the correct explanation of the assertion. |
|
(c) If assertion is true but reason is false. |
|
(d) If the assertion and reason both are false. |
If two lenses of +5 diopters are mounted at some distance apart, the equivalent power will always be negative if the distance is
|
(a) Greater than 40 cm |
(b) Equal to 40 cm |
|
(c) Equal to 10 cm |
(d) Less than 10 cm |
Which of the following is dependent on the intensity of incident radiation in a photoelectric experiment
|
(a) Work function of the surface |
|
(b) Amount of photoelectric current |
|
(c) Stopping potential will be reduced |
|
(d) Maximum kinetic energy of photoelectrons |
The radius of curvature for a convex lens is 40 cm, for each surface. Its refractive index is 1.5. The focal length will be
|
(a) 40 cm |
(b) 20 cm |
(c) 80 cm |
(d) 30 cm |
The resistor of resistance 'R' is connected to 25 V supply and heat produced in it is 25 J/sec. The value of R is
|
(a) 225 Ω |
(b) 1 Ω |
(c) 25 Ω |
(d) 50 Ω |
An electron jumps from 5th orbit to 4th orbit of hydrogen atom. Taking the Rydberg constant as 
per metre. What will be the frequency of radiation emitted
|
(a) 6.75 |
(b) 6.75 |
(c) 6.75 |
(d) None of these |
A man cannot see clearly the objects beyond a distance of 20 cm from his eyes. To see distant objects clearly he must use which kind of lenses and of what focal length
|
(a) 100 cm convex |
(b) 100 cm concave |
(c) 20 cm convex |
(d) 20 cm concave |
