Explanation:
When comb is rubbed to hair, it induces negative charge due to friction. When it is brought close to paper bits, they get polarized and the positive part sticks to the comb due to electrostatic attraction.
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An electron passing through a potential difference of 4.9 V collides with a mercury atom and transfers it to the first excited state. What is the wavelength of a photon corresponding to the transition of the mercury atom to its normal state
|
(a) 2050 Å |
(b) 2240 Å |
(c) 2525 Å |
(d) 2935 Å |
In charging a battery of motor-car, the following effect of electric current is used
|
(a) Magnetic |
(b) Heating |
(c) Chemical |
(d) Induction |
Astigmatism (for a human eye) can be removed by using
|
(a) Concave lens |
(b) Convex lens |
(c) Cylindrical lens |
(d) Prismatic lens |
Five lumen/watt is the luminous efficiency of a lamp and its luminous intensity is 35 candela. The power of the lamp is
|
(a) 80 W |
(b) 176 W |
(c) 88 W |
(d) 36 W |
The electric potential V is given as a function of distance x (metre) by 
)volt. Value of electric field at x = 1 is
|
(a) 20 V/m |
(b) 6 V/m |
(c) 11 V/m |
(d) -23 V/m |