How does a cell phone charger produce a voltage of 5V from the line voltage of 230V?

A circuit has a resistance and a reactance each equal to 100 Omega .Find its power factor. If the circuit draws a current of 1.5 A for an applied voltage of 200 V, what is the average power consumed in the circuit?

When a voltage measuring device is connected to ac mains, the meter shows the steady input voltage of 220 V.This means

At what value should the variable resistor be set such that the bridge is balanced? If the source voltage is 30 V find the value of the output voltage across XY, when the bridge is balanced.

In a step up transformer, the input voltage is 300 V and the output voltage is 15 kV. Then the ratio of the number of turns in the primary to that in the secondary is

A battery having e.m.f. 5V and internal resistance 0.5 is connected with a resistance of 4.5 Omega , then the voltage at the terminals of the battery is

Voltmeters V_(1) and V_(2) are connected in series across a D.C. line V_(1) reads 80 volts and has a per volt resistance of 200 ohms , V_(2) has a total resistance of 32 kilo ohms. The line voltage is

Nowadays, an electronic device - the cell phone - is very popular. From a mobile shop near your house, find out how they dispose off old and broken down cell phones.

solar cell producs photo voltage whwn incident light has eenrgy

The peak voltageof an a.c. supply is 300V. What is the rms voltage?