The sun emits a light with maximum wavelength 510 mm while another star X emits a light with maximum wavelength of 350 nm. What is the ratio of surface temperature of sun and the star X
|
(a) 2.1 |
(b) 0.68 |
(c) 0.46 |
(d) 1.45 |
(b) 0.68
Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.
A circular loop carrying a current is replaced by an equivalent magnetic dipole. A point on the axis of the loop is
|
(a) An end-on position |
(b) A broad side-on position |
|
(c) Both (a) and (b) |
(d) Neither (a) nor (b) |
Huygen wave theory allows us to know
|
(a) The wavelength of the wave |
(b) The velocity of the wave |
|
(c) The amplitude of the wave |
(d) The propagation of wave fronts |
A very long straight wire carries a current I. At the instant when a charge +Q at point P has velocity 
, as shown, the force on the charge is
|
(a) Opposite to OX |
(b) Along OX |
(c) Opposite to OY |
(d) Along OY |
An a particle is accelerated through a p.d of 
volt then K.E. of particle will be
|
(a) 8 MeV |
(b) 4 MeV |
(c) 2 MeV |
(d) 1 MeV |
Assertion : Electron has higher mobility than hole in a semiconductor.
Reason : Mass of electron is less than the mass of hole.
|
(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. |
When light falls on a metal surface, the maximum kinetic energy of the emitted photo-electrons depends upon
|
(a) The time for which light falls on the metal |
|
(b) Frequency of the incident light |
|
(c) Intensity of the incident light |
|
(d) Velocity of the incident light |