Advertisements
Advertisements
Question
Give a scientific reason:
For electric power transmission, copper or aluminium wire is used.
Advertisements
Solution
- Copper and aluminium have very low resistivity, hence less resistance for long wires.
- Low resistance causes less I2R heat loss, so energy loss is reduced.
- Both are good conductors that allow large currents to pass safely.
- Aluminium is lighter and cheaper, copper has higher conductivity; both are ductile and can be drawn into long wires.
Therefore, copper or aluminium wires are used to transmit electricity.
APPEARS IN
RELATED QUESTIONS
When current is switched ‘on’ in a room heater, it ______.
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?
Derive the expression for the heat produced due to a current 'I' flowing for a time interval 't' through a resistor 'R' having a potential difference 'V' across its ends. With which name is this relation known?
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).
Rewrite the following statement by selecting the correct option:
1 A = ____________ mA.
In an electric bulb, coil of _______ metal is used.
What is used to turn off the sudden increase in current in the electrical circuit of the house nowadays?
Write two devices based on the heating effect of electric current.
Right or wrong sentence.
Live wire and neutral wires have a 220 V potential difference.
Write scientific reason.
A coil made up of alloy Nichrome is used in the electric heater cooker as a resistor.
Explain the importance/uses of fuse wire.
What does overloading cause?
How can overloading be avoided?
Name some devices that run using heat effect of electric current
A fuse wire repeatedly gets burnt when used with a good heater. It is advised to use a fuse wire of:
Assertion: Bending of wire decreases the resistance of the electric wire.
Reason: The resistance of a conductor depends on length, thickness, nature of material and temperature of the conductor.
Why is parallel arrangement used in domestic wiring?
When a switch is in OFF position,
- circuit starting from the positive terminal of the cell stops at the switch.
- circuit is open.
- no current flows through it.
- current flows after some time.
Choose the combination of correct answer from the following.
Unscramble the following words:
SFEU
Can we use the same fuse in a geyser and a television set? Explain.
An MCB can be used instead of a fuse in an electrical circuit.
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 |
Name a few appliances which work on the basis of the heating effect of current.
The following is not a safety device.
An electric fuse is a wire made up of a material having ______ melting point.
A trip switch is a ______ safety device.
A fuse is used in an electric circuit to stop high currents flowing through the circuit.
The electric fuse works on the Joule heating principle.
Explain why fuse wire is always connected in a series arrangement.
If 220 V potential difference is applied across an electric bulb, a current of 0.45 A flows in the bulb. What must be the power of the bulb?
In which of the following applications of Iron, rusting will occur most? Support your answer with valid reason.
| A | B | C | D |
 |
 |
 |
 |
In a set up the students coated iron nails with zinc metal and noted that, iron nails coated with zinc prevents rusting. They also observed that zinc initially acts as a physical barrier, but an extra advantage of using zinc is that it continues to prevent rusting even if the layer of zinc is damaged. Name this process of rust prevention and give any two other methods to prevent rusting.
When a current I flows through a wire of resistance R for time t then the electrical energy produced is given by ______.
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.
