Advertisements
Advertisements
Question
How does the resistance of a wire vary with its:
diameter?
Advertisements
Solution
We know that the area of cross-section, A = πr2 = π (d / 2)2, where r is the radius and d is the diameter of the wire. So on increasing the diameter of the wire, its resistance decreases.
APPEARS IN
RELATED QUESTIONS
Compute the heat generated while transferring 96000 coulomb of charge in one hour through a potential difference of 50 V.
An electric heater of resistance 8 Ω draws 15 A from the service mains 2 hours. Calculate the rate at which heat is developed in the heater.
The safety device based on the heating effect of electric current is called a ______.
Why does the connecting cord of an electric heater not glow hot while the heating element does?
The current passing through an electric kettle has been doubled. The heat produced will become:
(a) half
(b) double
(c) four time
(d) one-fourth
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?
Statement 1 : Electric current ( flow of electrons ) creates heat in the resistor.
Statement 2 : Heat in the resistor is created according to the rule of energy conservation.
Explain Statement 1 with the help of Statement 2.
Write scientific reason.
A coil made up of alloy Nichrome is used in the electric heater cooker as a resistor.
What does overloading cause?
Heating effect of current is called ______
Which of the following is correct?
An electric iron consumes energy at the rate of 420 W when heating is at the maximum rate and 180 W when heating is at the minimum rate. The applied voltage is 220 V. What is the current in each case?
Why is parallel arrangement used in domestic wiring?
Three incandescent bulbs of 100 W each are connected in series in an electric circuit. In another circuit another set of three bulbs of the same wattage are connected in parallel to the same source.
- Will the bulb in the two circuits glow with the same brightness? Justify your answer.
- Now let one bulb in both the circuits get fused. Will the rest of the bulbs continue to glow in each circuit? Give reason.
Name two electric devices for each where
- heating effect of current is used and
- magnetic effect of current is used.
An MCB can be used instead of a fuse in an electrical circuit.
It would cost a man Rs. 3.50 to buy 1.0 kW h of electrical energy from the Main Electricity Board. His generator has a maximum power of 2.0 kW. The generator produces energy at this maximum power for 3 hours. Calculate how much it would cost to buy the same amount of energy from the Main Electricity Board.
Match the following
| 1. | Bulb | a. | Conductor |
| 2. | Electroplating | b. |
Insulator |
| 3. | Pure water | c. | Heating effect of current |
| 4. | Salt solution | d. | Chemical effect of current |
An electric fuse is a wire made up of a material having ______ melting point.
A trip switch is a ______ safety device.
