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प्रश्न
These days when current in the circuit suddenly increases _______ switches are used.
विकल्प
MCA
MCC
MCD
MCB
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उत्तर
These days when current in the circuit suddenly increases MCB switches are used.
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संबंधित प्रश्न
Give two reasons why nichrome alloy is used for making the heating elements of electrical appliances.
Why are the coils of electric irons and electric toasters made of an alloy rather than a pure metal?
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?
Write down the formula for the heat produced when a current I is passed through a resistor R for time t.
A resistance of 25 Ω is connected to a 12 V battery. Calculate the heat energy in joules generated per minute.
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 elements of electrical heating devices are usually made of:
(a) tungsten
(b) bronze
(c) nichrome
(d) argon
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
The electrical resistivities of four materials P, Q, R and S are given below:
| P | `6.84xx10^8`Ωm |
| Q | `1.70xx10^8`Ωm |
| R | ` 1.0xx10^15`Ωm |
| s | `11.0xx10^-7`Ωm |
Which material will you use for making: (a) heating element of electric iron (b) connecting wires of electric iron (c) covering of connecting wires? Give reason for your choice in each case.
How does the wire in the filament of a light bulb behave differently to the other wires in the circuit when the current flows?
What property of the filament wire accounts for this difference?
Two exactly similar heating resistances are connected (i) in series, and (ii) in parallel, in two different circuits, one by one. If the same current is passed through both the combinations, is more heat obtained per minute when they are connected in series or when they are connected in parallel? Give reason for your answer.
Identify the figure and give its use.
Identify the figure and give its use.
Give scientific reason :
In the electric equipment producing heat e.g. iron, electric heater, boiler, toaster, etc., an alloy such as Nichrome is used, not pure metals.
Which of the following substance contracts on heating?
Find the odd one out and give its explanation.
When does overloading occur?
How can overloading be avoided?
True or False – If False give the correct answer
The fuse wire does not melts whenever there is overload in the wiring.
Name any two appliances which work under the principle of heating effect of current.
An electric iron draws a current of 4 A when connected to 220 V mains. Its resistance must be:
Which of the following gases are filled in electric bulbs?
How does use of a fuse wire protect electrical appliances?
An electric component used as a safety device is electric circuit is ______.
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.
An electric cell produces electricity from the ______ ______ in it.
Can we use the same fuse in a geyser and a television set? Explain.
Name two electric devices for each where
- heating effect of current is used and
- magnetic effect of current is used.
Your teacher has shown you the following activity.
Activity: Teacher has wound a long insulated piece of wire around an iron nail in the form of a coil. Free ends of the wire are connected to a cell through a switch as shown in the following figure. The current is switched on and some pins are placed near the ends of the nail.
Write down any three questions that come to your mind about this activity.
What are the factors affecting heating effect of electric current?
______ wire is used in the filament of the bulbs.
Name the effect of the current responsible for the glow of the bulb in an electrical circuit.
A fuse is used in an electric circuit to stop high currents flowing through the circuit.
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?
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.
