- Aincreases
- ✓decreases
- Cremains unchanged
- Dfirst decreases and then increases
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A wire of length 5 m and radius 1 mm has a resistance of 1 ohm. What length of the wire of the same material at the same temperature and of radius 2 mm will also have a resistance of 1 ohm
|
(a) 1.25 m |
(b) 2.5 m |
(c) 10 m |
(d) 20 m |
Three bulbs of 40 W, 60 W, 100 W are arranged in series with 220 volt supply which bulb has minimum resistance
|
(a) 100 W |
(b) 40 W |
(c) 60 W |
(d) Equal in all bulbs |
The angle of dip at the magnetic equator is
| (a) 0° | (b) 45° | (c) 30° | (d) 90° |
The magnetic field near a current carrying conductor is given by
|
(a) Coulomb’s law |
(b) Lenz’ law |
(c) Biot-savart’s law |
(d) Kirchoff’s law |
A coil takes 15 min to boil a certain amount of water, another coil takes 20 min for the same process. Time taken to boil the same amount of water when both coil are connected in series
|
(a) 5 min |
(b) 8.6 min |
(c) 35 min |
(d) 30 min |
The magnetic field lines due to a bar magnet are correctly shown in
|
(a)
|
(b)
|
(c)
|
(d)
|
Function of rectifier is
|
(a) To convert ac into dc |
(b) To convert dc into ac |
|
(c) Both (a) and (b) |
(d) None of these |
Conditions of diffraction is
|
(a) |
(b) |
(c) |
(d) None of these |