Advertisements
Advertisements
Question
Tara, after completing her exams, went to her grandmother's house along with her younger brother Rahul. One day, Rahul came home after playing and switched on the fan and air conditioner. At the same time, his grandmother was preparing a milkshake for him using a mixer. Suddenly, they heard a big sound and the electricity of the house got shut down. Tara is called an electrician. He said the main reason for supply to shut down was overloading.
- What is overloading?
- Is overloading and short the same? When does short-circuiting take place?
- How can the effects of overloading be avoided?
Advertisements
Solution
- Overloading is the term used to describe the circuit's current flow when it exceeds the allowed value.
- Short-circuiting and overloading are not the same. When a live wire and a neutral wire are in direct contact with one another, a short circuit occurs.
- Overloading can be avoided by not connecting too many appliances to the same circuit at the same time.
APPEARS IN
RELATED QUESTIONS
Why does the cord of an electric heater not glow while the heating element does?
Why is the tungsten used almost exclusively for filament of electric lamps?
Give two reasons why nichrome alloy is used for making the heating elements of electrical appliances.
How does the resistance of a wire vary with its:
diameter?
Write down the formula for the heat produced when a current I is passed through a resistor R for time t.
How much heat will an instrument of 12 W produce in one minute if it is connected to the heat produced by it?
The current passing through a room heater has been halved. What will happen to the heat produced by it?
The heat produced by passing an electric current through a fixed resistor is proportional to the square of:
(a) magnitude of resistance of the resistor
(b) temperature of the resistor
(c) magnitude of current
(d) time for which current is passed
The heat produced in a wire of resistance 'x' when a current 'y' flows through it in time 'z' is given by:
(a) x2 × y × z
(b) x × z × y2
(c) y × z2 × x
(d) y × z × x
Identify the figure and give its use.

Identify the figure and give its use.

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.
Why does tungsten metal used to make solenoid type coil in an electric bulb?
Rewrite the following statement by selecting the correct option:
1 A = ____________ mA.
Write the mathematical expression for Joule’s law of heating.
The electricity bill specifies the usage in _______.
A coil of an alloy _______ is used in electric heater cooker as a resistor.
What is the heating effect of electric current?
Which metal is used to make the filament of an electric bulb?
What is used to turn off the sudden increase in current in the electrical circuit of the house nowadays?
True or False – If False give the correct answer
The fuse wire does not melts whenever there is overload in the wiring.
Define fuse.
Name some devices that run using heat effect of electric current
Which of the following is correct?
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.
An electric bulb is connected to a 220 V generator. The current is 0.50 A. What is the power of the bulb?
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.
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.
Paheli took a wire of length 10 cm. Boojho took a wire of 5 cm of the same material and thickness. Both of them connected the wires as shown in the circuit given in the following figure. The current flowing in both the circuits is the same.
- Will the heat produced in both cases be equal? Explain.
- Will the heat produced be the same if the wires taken by them are of equal lengths but of different thickness? Explain.

______ wire is used in the filament of the bulbs.
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.
A trip switch is a ______ safety device.
The electric fuse works on the Joule heating principle.
In the electric equipment producing heat like iron, electric heater, boiler, toaster etc., an alloy such as nichrome is used, not pure metals.
Two students decided to investigate the effect of water and air on iron object under identical experimental conditions. They measured the mass of each object before placing it partially immersed in 10 ml of water. After a few days, the object were removed, dried and their masses were measured. The table shows their results.
| Student | Object | Mass of Object before Rusting in g |
Mass of the coated object in g |
| A | Nail | 3.0 | 3.15 |
| B | Thin plate | 6.0 | 6.33 |
What might be the reason for the varied observations of the two students?
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?
An electric kettle of 2 kW is used for 2h. Calculate the energy consumed in
- kilowatt hour and
- joules.
