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प्रश्न
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उत्तर
Variable resistors consist of a resistance track with connections at both ends and a wiper which moves along the track as you turn the spindle. The track may be made from carbon, cermet (ceramic and metal mixture), or a coil of wire (for low resistances). The track is usually rotary but straight track versions, usually called sliders, are also available.
Variable resistance is a device used to change the resistance and hence the current flowing through a circuit; without changing the voltage.
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संबंधित प्रश्न
When starter motor of a car is switched on for 0.8 s . a charge 24 C passes through the coil of the motor . Calculate the current in the coil .
A cell of potential difference 12 V is connected to a bulb. The resistance of filament of bulb when it glows is 24Ω. Find the current drawn from the cell.
A bulb draws current 1.5 A at 6.0 V. Find the resistance of filament of bulb while glowing.
State two characteristics of resistances in the series circuit.
The following figure shows a metal rod PQ mounted on an insulated stand. The cap of an uncharged electroscope touches one end Q of the metal rod. A negatively charged ebonite rod is brought near the other end P of the metal rod.
(a) What charge does the end P have?
(b) What charge does the end Q have?
(c) What charge does the cap of the electroscope have?
(d) What charge does the gold leaf have?
(e) Will the leaf diverge or collapse? Give reason.
(f) If the electroscope is now earthed, what charge does the metal rod have?
