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The diagram below shows two coils A and B placed parallel to each other at a very small distance. Coil A is connected to an ac supply. G is a very sensitive galvanometer. When the key is closed
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(a) Constant deflection will be observed in the galvanometer for 50 Hz supply |
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(b) Visible small variations will be observed in the galvanometer for 50 Hz input |
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(c) Oscillations in the galvanometer may be observed when the input ac voltage has a frequency of 1 to 2 Hz |
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(d) No variation will be observed in the galvanometer even when the input ac voltage is 1 or 2 Hz |
If the minimum wavelength obtained in an X-ray tube is 2.5 
, the operating potential of the tube will be
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(a) 2 kV |
(b) 3 kV |
(c) 4 kV |
(d) 5 kV |
The mutual characteristic curves of a triode are as shown in figure. The cut off voltage for the triode is
| (a) 0 V | (b) 2 V | (c) – 4 V | (d) 6 V |
An electron beam in an X-ray tube is accelerated through a potential difference of 50000 volts. These are then made to fall on a tungsten target. The shortest wavelength of the X-ray emitted by the tube is
| (a) 2.5 Å | (b) 0.25 nm | (c) 0.25 cm | (d) 0.025 nm |
The ratio of electric fields on the axis and at equator of an electric dipole will be
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(a) 1 : 1 |
(b) 2 : 1 |
(c) 4 : 1 |
(d) None of these |
The equation 
is
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(a) b -emission |
(b) a -emission |
(c) e– capture |
(d) Fission |
A point object O is placed on the principal axis of a convex lens of focal length 20 cm at a distance of 40 cm to the left of it. The diameter of the lens is 10 cm. If the eye is placed 60 cm to the right of the lens at a distance h below the principal axis, then the maximum value of h to see the image will be
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(a) 0 |
(b) 5 cm |
(c) 2.5 cm |
(d) 10 cm |