Electromagnetic waves travel in a medium which has relative permeability 1.3 and relative permittivity 2.14. Then the speed of the electromagnetic wave in the medium will be
|
(a) 13.6 |
(b) 1.8 |
(c) 3.6 |
(d) 1.8 |
(d) 1.8 
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Water boils in an electric kettle in 15 minutes after switching on. If the length of the heating wire is decreased to 2/3 of its initial value, then the same amount of water will boil with the same supply voltage in
|
(a) 15 minutes |
(b) 12 minutes |
(c) 10 minutes |
(d) 8 minutes |
In circuit shown below, the resistances are given in ohms and the battery is assumed ideal with emf equal to 3 volt. The voltage across the resistance R4 is
|
(a) 0.4 V |
(b) 0.6 V |
(c) 1.2 V |
(d) 1.5 V |
Two charges + 5μC and +10 μC are placed 20 cm apart. The net electric field at the mid-Point between the two charges is
|
(a) 4.5 |
|
(b) 4.5 |
|
(c) 13.5 |
|
(d) 13.5 |
A condenser of capacitance 10 μF has been charged to 100 volts. It is now connected to another uncharged condenser in parallel. The common potential becomes 40 volts. The capacitance of another condenser is
|
(a) 15 μF |
(b) 5 μF |
(c) 10 μF |
(d) 16.6 μF |
For a thermocouple, the neutral temperature is 270℃ and the temperature of its cold junction is 20℃. If there is no deflection in the galvanometer, the temperature of the hot junction should be
|
(a) 210 ℃ |
(b) 540 ℃ |
(c) 520 ℃ |
(d) 209 ℃ |
