- ADiamagnetic materials.
- BFerromagnetic materials.
- CParamagnetic materials.
- DFerrimagnetic materials.
Explanation:
The relative permeability of ferromagnetic materials is much larger than 1. Ferromagnetic substances are those, which when placed in a magnetic field are strongly magnetized in the direction of the magnetizing field, i.e., it is strongly attracted by a magnet.
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A heater of 220 V heats a volume of water in 5 minute time. A heater of 110 V heats the same volume of water in
|
(a) 5 minutes |
(b) 8 minutes |
(c) 10 minutes |
(d) 20 minutes |
A body of capacity 4μF is charged to 80 V and another body of capacity 6μF is charged to 30V. When they are connected the energy lost by 4 μF capacitor is
|
(a) 7.8 mJ |
(b) 4.6 mJ |
(c) 3.2 mJ |
(d) 2.5 mJ |
A heating coil can heat the water of a vessel from 20℃ to 60℃ in 30 minutes. Two such heating coils are put in series and then used to heat the same amount of water through the same temperature range. The time taken now will be (neglecting thermal capacity of the coils)
|
(a) 60 minutes |
(b) 30 minutes
|
(c) 15 minutes |
(d) 7.5 minutes |
In the circuit as shown in the figure, the heat produced by 6 ohm resistance due to current flowing in it is 60 calorie per second. The heat generated across 3 ohm resistance per second will be

|
(a) 30 calorie |
(b) 60 calorie |
(c) 100 calorie |
(d) 120 calorie |