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प्रश्न
Find the odd one out.
पर्याय
Heater
Toaster
Electric bulb
Electric iron
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उत्तर
Electric bulb
Explanation:
Electric bulbs use tungsten filaments, but others have nichrome filaments.
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संबंधित प्रश्न
Why does the cord of an electric heater not glow while the heating element does?
Why are the conductors of electric heating devices, such as bread-toasters and electric irons, made of an alloy rather than a pure metal?
Write Joule's law of heating.
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?
An electric room heater draws a current of 2.4 A from the 120 V supply line. What current will this room heater draw when connected to 240 V supply line?
Give two reasons why nichrome alloy is used for making the heating elements of electrical appliances.
Why is a series arrangement not used for connecting domestic electrical appliances in a circuit?
An electric kettle rated at 220 V, 2.2 kW, works for 3 hours. Find the energy consumed and the current drawn.
Explain why, the current that makes the heater element very hot, only slightly warms the connecting wires leading to the heater.
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?
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
If the current flowing through a fixed resistor is halved, the heat produced in it will become:
Give a scientific reason:
For electric power transmission, copper or aluminium wire is used.
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.
The ‘live’ and the ‘neutral’ wires have potential difference of _______.
Which of the following substance contracts on heating?
What is a short circuit?
How can overloading be avoided?
Name some devices that run using heat effect of electric current
Which of the following is correct?
An electric iron draws a current of 4 A when connected to 220 V mains. Its resistance must be:
An electric bulb is connected to a 220 V generator. The current is 0.50 A. What is the power of the bulb?
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.
Name two electric devices for each where
- heating effect of current is used and
- magnetic effect of current is used.
An electric fuse has a body made of ceramic and two points for connecting the fuse wire.
______ 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.
A trip switch is a ______ safety device.
Explain why fuse wire is always connected in a series arrangement.
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?
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.
An electric iron of resistance 20 Ω draws a current of 5 A. The heat developed in the iron in 30 seconds is ______.
