Advertisements
Advertisements
Question
Give a scientific reason.
Tungsten metal is used to make a solenoid type coil in an electric bulb.
Advertisements
Solution 1
- The electric bulb operates under the principle of the heating effect of electric current.
- The bulb’s solenoid-type coil has a very high melting point and high resistance.
- The solenoid-type coil of the lightbulb becomes heated to a high temperature (up to 3400°C) and begins to shine when current is delivered through it.
As a result, tungsten metal creates a solenoid-type coil in an electric bulb.
Solution 2
- The temperature of a bulb’s filament determines how much light it emits. It rises as the temperature does.
- The material used to construct a lightbulb's filament should have a very high melting point so that it can be heated to a high temperature by running a current through it without melting. We are able to get more light as a result. Tungsten has an extremely high melting point. It is possible to heat tungsten wire to around 3400°C.
Hence, tungsten is used to make a solenoid type coil (filament) in an electric bulb.
APPEARS IN
RELATED QUESTIONS
State four most common electrical appliances based on heating effect of electric current. Why do we use finely heated platinum wire in surgery?
Compute the heat generated while transferring 96000 coulomb of charge in one hour through a potential difference of 50 V.
Why are the coils of electric irons and electric toasters made of an alloy rather than a pure metal?
A heating coil has a resistance of 200 Ω. At what rate will heat be produced in it when a current of 2.5 A flows through it?
A resistance of 25 Ω is connected to a 12 V battery. Calculate the heat energy in joules generated per minute.
Name the material which is used for making the filaments of an electric bulb.
The elements of electrical heating devices are usually made of:
(a) tungsten
(b) bronze
(c) nichrome
(d) argon
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
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.
An electric iron is connected to the mains power supply of 220 V. When the electric iron is adjusted at ‘minimum heating' it consumes a power of 360 W but at 'maximum heating’ it takes a power of 840 W. Calculate the current and resistance in each case.
Which electric heating device in your home do you think have resistors which control the flow of electricity?
Give a scientific reason:
For electric power transmission, copper or aluminium wire is used.
Solve the following example.
Two tungsten bulbs of wattage 100 W and 60 W power work on 220 V potential difference. If they are connected in parallel, how much current will flow in the main conductor?
Name the factors on which the heat produced in a wire depends when current is passed in it, and state how does it depend on the factors stated by you.
These days when current in the circuit suddenly increases _______ switches are used.
Write two devices based on the heating effect of electric current.
Explain the application of heating effect of electric current in an electric bulb with a diagram.
True or False – If False give the correct answer
The fuse wire does not melts whenever there is overload in the wiring.
A fuse wire repeatedly gets burnt when used with a good heater. It is advised to use a fuse wire of:
Which of the following gases are filled in electric bulbs?
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.
How does use of a fuse wire protect electrical appliances?
What is an electric fuse made up of?
It would cost a man Rs. 3.50 to buy 1.0 kW h of electrical energy from the Main Electricity Board. His generator has a maximum power of 2.0 kW. The generator produces energy at this maximum power for 3 hours. Calculate how much it would cost to buy the same amount of energy from the Main Electricity Board.
The following is not a safety device.
An electric fuse is a wire made up of a material having ______ melting point.
An electrochemical cell converts ______ energy into ______ energy.
Define the following:
Electrolyte
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?
In the electric equipment producing heat like iron, electric heater, boiler, toaster etc., an alloy such as nichrome is used, not pure metals.
What is the heating effect of electric current?
State the law that explains the heating effect of current with respect to the measurable properties in an electrical circuit.
When a current I flows through a wire of resistance R for time t then the electrical energy produced is given by ______.
An electric iron of resistance 20 Ω draws a current of 5 A. The heat developed in the iron in 30 seconds is ______.
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.
