Electrical Energy and Electrical Power

In the circuit given, consider $R_1=r$, $R_2=2r$ and power supply of voltage $V$.

Determine the power consumed by the circuit in each of the following instances:

i. when the switch is open

ii. when the switch is closed

iii. while the switch is closed, the resistor $R_2$ is heated so that its resistance is doubled.

An electric kettle has a power rating of $2000 \mathrm{W}$. It takes $90 \mathrm{seconds}$ to heat $500 \mathrm{g}$ water from $20 °\mathrm{C}$ to boiling. Use this information to calculate approximate value for the specific heat capacity of water.​

A metallic coil connected to a $220 \mathrm{V}$ supply, has a resistance of $110 \mathrm{\Omega }$ (while hot) How long will this coil take to heat $1 \mathrm{kg}$ of water from $20 °\mathrm{C}$ to $70 °\mathrm{C}$? Assume that whole of the heat produced by the coil is taken up by water. (Heat capacity of water= $4186 \mathrm{J}/\mathrm{kg} °\mathrm{C}$) 
 

Calculate the total power dissipated in the circuit.

In the circuit shown, a parallel combination of a coil of inductance $L$ and a resistance $R$ can be connected across a battery of electromotive force $\mathcal{E}$ and internal resistance $r$ through a switch. Find total heat dissipated in the resistance $R$ after the switch is closed.

Two bulbs $25 \mathrm{W}-220 \mathrm{V}$ and $100 \mathrm{W}-220 \mathrm{V}$ are given. Which has higher resistance?

A wind generator provides power to a factory whose equipment operates at $120 \text{KW}$ and $240 \mathrm{V}$. The factory is connected to a wind generator with cables of total resistance of $0.80 \mathrm{\Omega }$.

It is suggested that a transformer be used to step up the voltage of the wind generator so that the step-down transformer near the factory would bring the voltage down from $2.4 \mathrm{KV}$ to $240 \mathrm{V}$.

Determine the power loss in the cables now. 

A wind generator provides power to a factory whose equipment operates at $120 \text{KW}$ and $240 \mathrm{V}$. The factory is connected to a wind generator with cables of total resistance of $0.80 \mathrm{\Omega }$.

Calculate the efficiency of the transmission system.

A wind generator provides power to a factory whose equipment operates at $120 \text{KW}$ and $240 \mathrm{V}$. The factory is connected to a wind generator with cables of total resistance of $0.80 \mathrm{\Omega }$.

Calculate the voltage at the wind generator.

A wind generator provides power to a factory whose equipment operates at $120 \text{KW}$ and $240 \mathrm{V}$. The factory is connected to a wind generator with cables of total resistance of $0.80 \mathrm{\Omega }$.

Calculate the power lost in the cables.

A wind generator provides power to a factory whose equipment operates at $120 \text{KW}$ and $240 \mathrm{V}$. The factory is connected to a wind generator with cables of total resistance of $0.80 \mathrm{\Omega }$.

It is suggested that a transformer be used to step up the voltage of the wind generator so that the step-down transformer near the factory would bring the voltage down from $2.4 \mathrm{KV}$ to $240 \mathrm{V}$.

Determine the power loss in the cables now. 

A wind generator provides power to a factory whose equipment operates at $120 \text{KW}$ and $240 \mathrm{V}$. The factory is connected to a wind generator with cables of total resistance of $0.80 \mathrm{\Omega }$.

Calculate the efficiency of the transmission line.

A wind generator provides power to a factory whose equipment operates at $120 \text{KW}$ and $240 \mathrm{V}$. The factory is connected to a wind generator with cables of total resistance of $0.80 \mathrm{\Omega }$.

Calculate the voltage at wind generator.

A wind generator provides power to a factory whose equipment operates at $120 \text{KW}$ and $240 \mathrm{V}$. The factory is connected to a wind generator with cables of total resistance of $0.80 \mathrm{\Omega }$.

Calculate the power lost in the cables.

Two $220 \mathrm{V}$, $100 \mathrm{W}$ bulbs are connected together. The combination is connected to a $220 \mathrm{V}$ AC supply line. The power drawn by the combination can be:

Three identical resistors each of resistance $R$ are connected to an ideal cell of voltage $V$ as shown. Total power dissipated in all three resistors is

If the cell of emf $5 \mathrm{V}$ shown in the figure, gives a power of $10 \mathrm{W}$, then, find the power consumed by the resistors $2 \mathrm{\Omega }$ and $1 \mathrm{\Omega }$.

In the given circuit, Find the value of $X$ such that the power generated in $1 \mathrm{\Omega }$ resistance will be maximum and then find the current flowing in the circuit if $E=3 \mathrm{V}$.

An electric bulb is rated $220 \mathrm{V}-100 \mathrm{W}$. The power consumed by it when operated on $110 \mathrm{V}$ will be (in watt)

An electric bulb is rated $220 \mathrm{V}-100 \mathrm{W}$. The power consumed by it when operated on $110 \mathrm{V}$ will be