Advertisements
Advertisements
प्रश्न
Explain why, tungsten is used for making the filaments of electric bulbs.
Advertisements
उत्तर
Tungsten is used for making the filaments of electric bulbs because it has a very high melting point (3380°C). It does not melt down and thus remains white hot.
APPEARS IN
संबंधित प्रश्न
When current is switched ‘on’ in a room heater, it ______.
The current passing through a room heater has been halved. What will happen to the heat produced by it?
If the current flowing through a fixed resistor is halved, the heat produced in it will become:
Three heaters each rated 250 W, 100 V are connected in parallel to a 100 V supply. Calculate:
- the total current taken from the supply
- the resistance of each heater and
- the energy supplied in kWh to the three heaters in 5 hours.
Give a scientific reason.
Tungsten metal is used to make a solenoid type coil in an electric bulb.
Identify the figure and give its use.
These days when current in the circuit suddenly increases _______ switches are used.
What is a short circuit?
What is overloading?
Write scientific reason.
A coil made up of alloy Nichrome is used in the electric heater cooker as a resistor.
A current of 1 A is drawn by a filament of an electric bulb. Number of electrons passing through a cross-section of the filament in 16 seconds would be roughly:
An electric bulb is connected to a 220 V generator. The current is 0.50 A. What is the power of the bulb?
What is Joule’s heating effect? How can it be demonstrated experimentally? List its four applications in daily life.
(a) Observe the diagram given below and state whether the bulb will glow or not when we switch on K.
(b) Is it safe to handle the bulb when the switch is OFF?
(c) Give a reason for your answer in (b).
Name two electric devices for each where
- heating effect of current is used and
- magnetic effect of current is used.
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.
An electrochemical cell converts ______ energy into ______ energy.
The electric fuse works on the Joule heating principle.
State the law that explains the heating effect of current with respect to the measurable properties in an electrical circuit.
