A coil and a bulb are connected in series with a dc source, a soft iron core is then inserted in the coil. Then
|
(a) Intensity of the bulb remains the same |
(b) Intensity of the bulb decreases |
|
(c) Intensity of the bulb increases |
(d) The bulb ceases to glow |
(b) Intensity of the bulb decreases
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X-rays of which of the following wavelengths are hardest
| (a) 4 Å | (b) 1 Å | (c) 0.1 Å | (d) 2 Å |
A radioactive nucleus with Z protons and N neutrons emits an a-particle, 2b-particles and 2 gamma rays. The number of protons and neutrons in the nucleus left after the decay respectively, are
|
(a) Z – 3, N – 1 |
(b) Z – 2, N – 2 |
(c) Z – 1, N – 3 |
(d) Z, N – 4 |
If all the resistors shown have the value 2 ohm each, the equivalent resistance over AB is
|
(a) 2 ohm |
(b) 4 ohm |
(c) 1 |
(d) 2 |
The focal length of a concave mirror is 50 cm. Where an object be placed so that its image is two times and inverted
|
(a) 75 cm |
(b) 72 cm |
(c) 63 cm |
(d) 50 cm |
In the circuit shown, the value of each resistance is r, then equivalent resistance of circuit between points A and B will be
|
(a) (4/3) r |
(b) 3r / 2 |
(c) r / 3 |
(d) 8r/7 |
A current of 16 ampere flows through molten NaCl for 10 minute. The amount of metallic sodium that appears at the negative electrode would be
|
(a) 0.23 gm |
(b) 1.15 gm |
(c) 2.3 gm |
(d) 11.5 gm |
A metallic ring connected to a rod oscillates freely like a pendulum. If now a magnetic field is applied in horizontal direction so that the pendulum now swings through the field, the pendulum will
|
(a) Keep oscillating with the old time period |
|
(b) Keep oscillating with a smaller time period |
|
(c) Keep oscillating with a larger time period |
|
(d) Come to rest very soon |
