A constant voltage is applied between the two ends of a metallic wire. If both the length and the radius of the wire are doubled, the rate of heat developed in the wire
|
(a) Will be doubled |
(b) Will be halved |
|
(c) Will remain the same |
(d) Will be quadrupled |
(a) Will be doubled
Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.
A steady current i flows in a small square loop of wire of side L in a horizontal plane. The loop is now folded about its middle such that half of it lies in a vertical plane. Let 
and 
respectively denote the magnetic moments due to the current loop before and after folding. Then
|
(a) |
(b) |
|
(c) |
(d) |
Assertion : Bohr had to postulate that the electrons in stationary orbits around the nucleus do not radiate.
Reason : According to classical physics all moving electrons radiate.
|
(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. |
The dispersive power is maximum for the material
|
(a) Flint glass |
(b) Crown glass |
(c) Mixture of both |
(d) None of the above |
A galvanometer with a resistance of 12 W gives full scale deflection when a current of 3 mA is passed. It is required to convert it into a voltmeter which can read up to 18 V. the resistance to be connected is
|
(a) 6000 W |
(b) 5988 W |
(c) 5000 W |
(d) 4988 W |
Assuming that universe is expanding, if the spectrum of light coming from a star which is going away from earth is tested, then in the wavelength of light
|
(a) There will be no change |
|
(b) The spectrum will move to infrared region |
|
(c) The spectrum will seems to shift to ultraviolet side |
|
(d) None of the above |
The k line of singly ionised calcium has a wavelength of 393.3 nm as measured on earth. In the spectrum of one of the observed galaxies, this spectral line is located at 401.8 nm. The speed with which the galaxy is moving away from us, will be
|
(a) 6480 km/s |
(b) 3240 km/s |
(c) 4240 km/sec |
(d) None of these |
A plane glass slab is kept over various coloured letters, the letter which appears least raised is
|
(a) Blue |
(b) Violet |
(c) Green |
(d) Red |
