Electric Charges and Fields — Physics STD 12 Science — Question

The electric field near a conducting surface having a uniform surface charge density σ  is given by

(a)  and is parallel to the surface	(b)  and is parallel to the surface
(c)  and is normal to the surface	(d)  and is normal to the surface

A galvanometer has a resistance of 25 ohm and a maximum of 0.01 A current can be passed through it.  In order to change it into an ammeter of range 10 A, the shunt resistance required is

(a) 5/999 ohm

(b) 10/999 ohm

(c) 20/999 ohm

(d) 25/999 ohm

The lamp whose working is based on a discharge tube is ________:

‘X’ is the phenomenon of making a region free from any electric field. Identify X.

A reaction between a proton and  that produces  must also liberate

(a)

(b)

(c)

(d)

Magnetic moment of a thin bar magnet is M. If it is cut first perpendicular to length and then perpendicular to breadth, then magnetic moment of obtained piece is:

Light  coming from a star is observed to have a wavelength of 3737 Å, while its real wavelength is 3700 Å. The speed of the star relative to the earth is [Speed of light 3 ]

(a) 3

(b) 3

(c) 3.7

(d) 3.7

The frequencies of X-rays, g-rays and ultraviolet rays are respectively a, b and c. Then

(a) a < b, b > c

(b) a > b, b > c

(c) a > b, b < c

(d) a < b, b < c

Which of the following statements is incorrect?

Which of the following logic gates is an universal gate?