Practice MCQ Questions and answers on Physics-GK

Using water for putting out electric fires is risky, as the firemen can be electrocuted by the water jet. Water is a good conductor of electricity, and, the electric current flows through the water-jet directly into the hands of the person who is holding the waterhose, resulting in immediate electrocution.

Brightness of bulb depends on both voltage and current. The brightness depends on power.
Since we know that Power (P) = Voltage x Current = V I
So whether you increase the current or the voltage the brightness will increase.

The resistance of a wire is directly proportional to its length and inversely proportional to its cross-sectional area. Resistance also depends on the material of the conductor.

An ohmic conductor is defined as a two-terminal device in which the voltage or current characteristics have a straight line passing through the origin. Silver, copper wire, metals are the examples of ohmic conductors.

according to rules 1/R = 1/R1 + 1/R2 (for parallel) =1/20 + 1/30 =12 ohm

The elements which will be malleable (thin sheets) and good conductors of electricity has to be a metal. Tin and Silver is correct answer.

Resistors are in parallel when each resistor is connected directly to the voltage source by connecting wires having negligible resistance. Each resistor thus has the full voltage of the source applied to it.When resistors are connected in parallel, more current flows from the source than would flow for any of them individually, so the total resistance is lower. Each resistor in parallel has the same full voltage of the source applied to it, but divide the total current among them.

Ampere second could be the unit of charge.

Conductivity is the capacity to transmit current or heat. Pure elemental silver is the best conductor of electricity. Copper, gold, aluminium are good conductors of electricity.