The counting rate observed from a radioactive source at t = 0 second was 1600 counts per second and at t = 8 seconds it was 100 counts per second. The counting rate observed, as counts per second at t = 6 seconds, will be
|
(a) 400 |
(b) 300 |
(c) 200 |
(d) 150 |
(c) 200
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Lux is equal to
|
(a) 1 lumen/m2 |
(b) 1 lumen/cm2 |
(c) 1 candela/m2 |
(d) 1 candela/cm2 |
When a battery is connected across a series combination of self inductance L and resistance R, the variation in the current i with time t is best represented by
|
(a)
|
(b)
|
(c)
|
(d) |
A charged particle moving in a magnetic field experiences a resultant force
|
(a) In the direction of field |
|
(b) In the direction opposite to that field |
|
(c) In the direction perpendicular to both the field and its velocity |
|
(d) None of the above |
The refraction of light is commonly known as:
A radioactive material has a half-life of 8 years. The activity of the material will decrease to about 1/8 of its original value in
|
(a) 256 year |
(b) 128 year |
(c) 64 year |
(d) 24 year |
When a body is earth connected, electrons from the earth flow into the body. This means the body is….
|
(a) Unchanged |
(b) Charged positively |
(c) Charged negatively |
(d) An insulator |
The magnifying power of a microscope with an objective of 5 mm focal length is 400. The length of its tube is 20 cm. Then the focal length of the eye-piece is
|
(a) 200 cm |
(b) 160 cm |
(c) 2.5 cm |
(d) 0.1 cm |
