State whether the following statements are true or false:
(a) To make a battery of two cells, the negative terminal of one cell is connected to the negative terminal of the other cell.
(b) A car battery is just one big cell.
(c) When the electric current through the fuse exceeds a certain limit, the fuse wire melts and break.
(d) A compact fluorescent lamp (CFL) has a filament in it.
(e) MCB works on the heating effect of electric current.
(f) The heating element of an electric iron is made of tungsten.
(g) Compact fluorescent lamp (CFL) works on the heating effect of current.
(h) An electromagnet does not attract a piece of iron.
(i) An electric bell has an electromagnet.
(j) An electromagnet is a temporary magnet.
(a) To make a battery of two cells, the negative terminal of one cell is connected to the negative terminal of the other cell. (False)
Explanation
In order to make a battery of two cells, the negative terminal of one cell is connected to the positive terminal of the other cell.
(b) A car battery is just one big cell. (False)
Explanation
A typical 12-volt car battery is composed of six cells, not one big cell.
(c) When the electric current through the fuse exceeds a certain limit, the fuse wire melts and break. (True)
Explanation
A fuse wire is a short-length wire of a low melting point. So if a large current exceeds a safe value (due to short-circuiting or overloading) it heats the fuse wire too much and the wire melts and breaks the circuit.
(d) A compact fluorescent lamp (CFL) has a filament in it. (False)
Explanation
A compact fluorescent lamp (CFL) contains argon and mercury vapour housed within a spiral-shaped tube, instead of a glowing filament.
(e) MCB works on the heating effect of electric current. (False)
Explanation
MCB does not work on the heating effect of current, rather it works on the magnetic effect of current.
(f) The heating element of an electric iron is made of tungsten. (False)
Explanation
The heating element of an electric iron is made of Nichrome, an alloy of 80% nickel and 20% chromium, because it has relatively high resistance and does not oxidize and burn easily at high-temperature (high melting and boiling point).
On the other hand, Tungsten oxidizes at red hot temperatures and eventually burn out unless protected from oxygen in the air by sealing in an inert gas atmosphere.
Also, tungsten is more expensive than nichrome.
(g) Compact fluorescent lamp (CFL) works on the heating effect of current. (False)
Explanation
The Compact fluorescent lamp (CFL) works on the principle of ionisation.
(h) An electromagnet does not attract a piece of iron. (False)
Explanation
An electromagnet is a temporary magnet that works when the current is passed through it. Therefore, it can attract a piece of iron.
(i) An electric bell has an electromagnet. (True)
Explanation
An electric bell works on the principle of electromagnetism. In an electric bell, a coil of an insulated wire is wrapped around a piece of iron, and when the current passes through the coil it behaves as an electromagnet.
(j) An electromagnet is a temporary magnet. (True)
Explanation
An electromagnet is a temporary magnet because it works as long as the electric current passes through it.
Related Articles
- Mark ‘T’ if the statement is true and ‘F’ if it is false:$(a)$. To make a battery of two cells, the negative terminal of one cell is connected to the negative terminal of the other cell. $(T/F)$$(b)$. When the electric current through the fuse exceeds a certain limit, the fuse wire melts and breaks. $(T/F)$$(c)$. An electromagnet does not attract a piece of iron. $(T/F)$$(d)$. An electric bell has an electromagnet. $(T/F)$
- State whether the following statements are true of false:(a) A wire with a green insulation is usually the live wire. (b) A miniature circuit breaker (MCB) works on the heating effect of current.
- Explain the term: Heating effect of electric current.
- Heating Effect of Electric Current
- When electric current is passed through a conducting solution, there is a change of colour of the solution. This indicates$(a)$. the chemical effect of current $(b)$. the heating effect of current$(c)$. the magnetic effect of current $(d)$. the lightning effect of current
- a) What is an electric current? What makes an electric current flow in a wire?b) Define the unit of electric current(or Define Ampere).
- Fill in the blanks:1. Our body is a ………………….. of electricity. 2. An electric cell produces electricity from the ………………….. in it. 3. In an electric circuit a fuse is a ………………….. to prevent possible fire. 4. A combination of two or more cells is called a ………………….. . 5. The coil of wire in an electric heater is called an ………………….. . 6. A ………………….. is a safety device which prevents damages to electrical circuits and possible fires. 7. The wire gets ………………….. when an electric current passes through it. 8. We must look for ………………….. mark on electrical appliances. 9. When electric current passes through a wire, it behaves like a magnet. It is the ………………….. effect of current. 10. Crane has a strong ………………….. attached to it.
- An MCB which cuts off the electricity supply in case of short-circuiting or overloading works on the:(a) chemical effect of current (b) heating effect of current (c) magnetic effect of current (d) electroplating effect of current
- (a) How should the electric lamps in a building be connected so that switching on or off in a room has no effect on other lamps in the building? State one more advantage of such an arrangement.(b) Which effect of current is utilised in the working of an electric fuse? How does an electric fuse work? (c) What is the usual colour of the insulation of (i) earth wire, and (1) live wire? (d) When does an electric short circuit occur? What harm can it do? (e) Explain the purpose of earthing an electrical appliance.
- When an electric current is passed through any wire, a magnetic field is produced around it. Then why an electric iron connecting cable does not attract nearby iron objects when electric current is switched on through it?
- (a) What is an electromagnet? Describe the construction and working of an electromagnet with the help of a labelled diagram.(b) Explain why, an electromagnet is called a temporary magnet. (c) Explain why, the core of an electromagnet should be of soft iron and not of steel. (d) State the factors on which the strength of an electromagnet depends. How does it depend on these factors? (e) Write some of the important uses of electromagnets.
- In a circuit, ______ current flows from the positive terminal of a cell to the negative terminal of the cell.
- Choose the statement which is not correct in the case of an electric fuse.$(a)$. Fuses are inserted in electric circuits of all buildings$(b)$. There is a maximum limit on the current which can safely flow through the electric circuits$(c)$. There is a minimum limit on the current which can safely flow in the electric circuits$(d)$. If a proper fuse is inserted in a circuit it will blow off if current exceeds the safe limit
- An electric current can produce$(a)$. heating effect $(b)$. chemical effect$(c)$. magnetic effect $(d)$. chemical, heating and magnetic effects
- (a) What is an electromagnet? List any two uses.(b) Draw a labelled diagram to show how an electromagnet is made.(c) State the purpose of soft iron core used in making an electromagnet.(d) List two ways of increasing the strength of an electromagnet if the material of the electromagnet is fixed.
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