Advertisements
Advertisements
प्रश्न
Heat energy is being produced in a resistance in a circuit at the rate of 100 W. The current of 3 A is flowing in the circuit. What must be the value of the resistance?
Advertisements
उत्तर
Given: Power, P = 100 W
Current, I = 3 A
Resistance, R = ?
We know, P = I2R
⇒ R = `P/I^2`
= `100/3^2`
= `100/9`
= 11.11 Ω
∴ The value of the resistance is 11.11 Ω.
APPEARS IN
संबंधित प्रश्न
Why is the tungsten used almost exclusively for filament of electric lamps?
The safety device based on the heating effect of electric current is called a ______.
An electric heater is connected to the 230 V mains supply. A current of 8 A flows through the heater.
(b) How much energy is transferred to the heater each second?
Why does the connecting cord of an electric heater not glow hot while the heating element does?
What is meant by the heating effect of current?
Name the material which is used for making the filaments of an electric bulb.
If the current flowing through a fixed resistor is halved, the heat produced in it will become:
The electrical resistivities of four materials P, Q, R and S are given below:
| P | `6.84xx10^8`Ωm |
| Q | `1.70xx10^8`Ωm |
| R | ` 1.0xx10^15`Ωm |
| s | `11.0xx10^-7`Ωm |
Which material will you use for making: (a) heating element of electric iron (b) connecting wires of electric iron (c) covering of connecting wires? Give reason for your choice in each case.
Which electric heating device in your home do you think have resistors which control the flow of electricity?
Identify the figure and give its use.
Solve the following example.
Two tungsten bulbs of wattage 100 W and 60 W power work on 220 V potential difference. If they are connected in parallel, how much current will flow in the main conductor?
An electric iron of 1100 W is operated for 2 hrs daily. What will be the electrical consumption expenses for that in the month of April? (The electric company charges Rs 5 per unit of energy).
The electricity bill specifies the usage in _______.
Which metal is used to make the filament of an electric bulb?
True or False – If False give the correct answer
The fuse wire does not melts whenever there is overload in the wiring.
Mark the correct choice
- Assertion: Electric appliances with a metallic body have three wire connections.
- Reason: Three-pin connections reduce the heating of the connecting wires.
A current of 1 A is drawn by a filament of an electric bulb. Number of electrons passing through a cross-section of the filament in 16 seconds would be roughly:
Which of the following gases are filled in electric bulbs?
Why is parallel arrangement used in domestic wiring?
Unscramble the following words:
SFEU
Your teacher has shown you the following activity.
Activity: Teacher has wound a long insulated piece of wire around an iron nail in the form of a coil. Free ends of the wire are connected to a cell through a switch as shown in the following figure. The current is switched on and some pins are placed near the ends of the nail.
Write down any three questions that come to your mind about this activity.
What are the factors affecting heating effect of electric current?
Assertion: A current-carrying wire should be charged.
Reason: The current in a wire is due to the flow of free electrons in a definite direction.
Name a few appliances which work on the basis of the heating effect of current.
An electrochemical cell converts ______ energy into ______ energy.
Find the odd one out.
1 kWh is equal to ______.
In the electric equipment producing heat like iron, electric heater, boiler, toaster etc., an alloy such as nichrome is used, not pure metals.
An electric kettle consumes 1 kW of electric power when operated at 220 V. A fuse wire of what rating must be used for it?
Write an expression for the amount of heat produced in a resistor when an electric current is passed through it stating the meanings of the symbols used.
State the law that explains the heating effect of current with respect to the measurable properties in an electrical circuit.
An electric iron is rated 220 V, 2 kW. If the iron is used for 3h daily find the cost of running it for one week if it costs ₹ 4.25 per kWh.
