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प्रश्न
Which of the following substance contracts on heating?
विकल्प
Lukewarm water
Ice
Iron
Mercury
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उत्तर
Ice
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संबंधित प्रश्न
Why does the cord of an electric heater not glow while the heating element does?
An electric heater is connected to the 230 V mains supply. A current of 8 A flows through the heater.
(a) How much charge flows around the circuit each second?
What is nichrome? State its one use.
How does the resistance of a wire vary with its:
diameter?
Why is a series arrangement not used for connecting domestic electrical appliances in a circuit?
Why does the connecting cord of an electric heater not glow hot while the heating element does?
Explain why, the current that makes the heater element very hot, only slightly warms the connecting wires leading to the heater.
An electric fuse works on the:
(a) chemical effect of current
(b) magnetic effect of current
(c) lighting effect of current
(d) heating effect of current
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
Which of the following characteristic is not suitable for a fuse wire?
(a) thin and short
(b) thick and short
(c) low melting point
(d) higher resistance than rest of wiring
Identify the figure and give its use.
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?
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what is the heating effect of the electric current? state any four applications of it?
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Find the odd one out and give its explanation.
Which metal is used to make the filament of an electric bulb?
What is a short circuit?
Write scientific reason.
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What does overloading cause?
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The heating element of an electric iron is made up of:
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(a) Observe the diagram given below and state whether the bulb will glow or not when we switch on K.
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(c) Give a reason for your answer in (b).
An electric component used as a safety device is electric circuit is ______.
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- Will the heat produced be the same if the wires taken by them are of equal lengths but of different thickness? Explain.
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______ wire is used in the filament of the bulbs.
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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 of 2 kW is used for 2h. Calculate the energy consumed in
- kilowatt hour and
- joules.
State the law that explains the heating effect of current with respect to the measurable properties in an electrical circuit.
An electric iron of resistance 20 Ω draws a current of 5 A. The heat developed in the iron in 30 seconds is ______.
