The valence band and conduction band of a solid overlap at low temperature, the solid may be
|
(a) A metal |
(b) A semiconductor |
(c) An insulator |
(d) None of these |
(a) A metal
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Work function of a metal is 2.51 eV. Its threshold frequency is
|
(a) 5.9 |
(b) 6.5 |
|
(c) 9.4 |
(d) 6.08 |
The length of a wire of a potentiometer is 100 cm, and the emf of its standard cell is E volt. It is employed to measure the e.m.f of a battery whose internal resistance is 0.5 W. If the balance point is obtained at l = 30 cm from the positive end, the e.m.f. of the battery is (where i is the current in the potentiometer)
|
(a) |
(b) |
(c) |
(d) |
A thin lens made of glass of refractive index m = 1.5 has a focal length equal to 12 cm in air. It is now immersed in water 
Its new focal length is
|
(a) 48 cm |
(b) 36 cm |
(c) 24 cm |
(d) 12 cm |
The current in a LR circuit builds up to 
th of its steady state value in 4s. The time constant of this circuit is
|
(a) |
(b) |
(c) |
(d) |
An electron moving with the speed 5 
per sec is shooted parallel to the electric field of intensity 1 
. Field is responsible for the retardation of motion of electron. Now evaluate the distance travelled by the electron before coming to rest for an instant (mass of e = 9 
. charge = 1.6 
)
|
(a) 7 m |
(b) 0.7 mm |
(c) 7 cm |
(d) 0.7 cm |
Assertion : The induced emf in a conducting loop of wire will be non zero when it rotates in a uniform magnetic field.
Reason : The emf is induced due to change in magnetic flux.
|
(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. |
Three capacitors are connected to D.C. source of 100 volts shown in the adjoining figure. If the charge accumulated on plates of 
and 
are 
and 
respectively, then
|
(a) |
(b) |
|
(c) |
(d) |
The maximum intensity of fringes in Young's experiment is I. If one of the slit is closed, then the intensity at that place becomes Io. Which of the following relation is true ?
|
(a) I = Io |
(b) I = 2Io |
|
(c) I = 4Io |
(d) There is no relation between I and Io |
