- AThe energy for the electron to enter into the metal
- BThe energy for producing X−ray
- CThe energy for the electron to come out from metal surface
- DNone of these
Explanation:
The work function of a metal is the energy for the electron to come out from metal surface.
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An equiconvex lens of glass of focal length 0.1 metre is cut along a plane perpendicular to principle axis into two equal parts. The ratio of focal length of new lenses formed is
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(a) 1 : 1 |
(b) 1 : 2 |
(c) 2 : 1 |
(d) 2 : |
A cube of a metal is given a positive charge Q. For the above system, which of the following statements is true
|
(a) Electric potential at the surface of the cube is zero |
|
(b) Electric potential within the cube is zero |
|
(c) Electric field is normal to the surface of the cube |
|
(d) Electric field varies within the cube |
The imaginary line passing through the pole and the center of curvature of the curved mirror is called its _______.
Lenz’s law applies to
|
(a) Electrostatics |
(b) Lenses |
|
(c) Electro-magnetic induction |
(d) Cinema slides |
A heavenly body is receding from earth such that the fractional change in l is 1, then its velocity is
|
(a) C |
(b) |
(c) |
(d) |
The shortest wavelength of X-rays emitted from an X-ray tube depends on the
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(a) Current in the tube |
(b) Voltage applied to the tube |
|
(c) Nature of gas in the tube |
(d) Atomic number of target material |