Advertisements
Advertisements
प्रश्न
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?
विकल्प
99 W
70 W
45 W
22 W
Advertisements
उत्तर
99 W
Explanation:
Given:
Potential difference = 220 V, Current = 0.45 A
Power (W) = Potential difference (V) × Current (A)
= 220 × 0.45 W
= 99 W
So, the bulb must be of power 99 W.
APPEARS IN
संबंधित प्रश्न
An electric iron of resistance 20 Ω takes a current of 5 A. Calculate the heat developed in 30 s.
Why are the conductors of electric heating devices, such as bread-toasters and electric irons, made of an alloy rather than a pure metal?
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.
What is meant by the heating effect of current? Give two applications of the heating effect of current.
The current passing through an electric kettle has been doubled. The heat produced will become:
(a) half
(b) double
(c) four time
(d) one-fourth
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
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?
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.
Give Scientific reason.
In practice, the unit kWh is used for the measurement of electrical energy, rather than joule.
An electric iron of 1100 W is operated for 2 hrs daily. What will be the electrical consumption expenses for that in the month of April? (The electric company charges Rs 5 per unit of energy).
In an electric bulb, coil of _______ metal is used.
These days when current in the circuit suddenly increases _______ switches are used.
What is the heating effect of electric current?
Which metal is used to make the filament of an electric bulb?
What is overloading?
What is used to turn off the sudden increase in current in the electrical circuit of the house nowadays?
Live wire and neutral wires have a 220 V potential difference.
Write scientific reason.
A coil made up of alloy Nichrome is used in the electric heater cooker as a resistor.
When does overloading occur?
How can overloading be avoided?
Why is parallel arrangement used in domestic wiring?
Three incandescent bulbs of 100 W each are connected in series in an electric circuit. In another circuit another set of three bulbs of the same wattage are connected in parallel to the same source.
- Will the bulb in the two circuits glow with the same brightness? Justify your answer.
- Now let one bulb in both the circuits get fused. Will the rest of the bulbs continue to glow in each circuit? Give reason.
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.
Name two electric devices for each where
- heating effect of current is used and
- magnetic effect of current is used.
An MCB can be used instead of a fuse in an electrical circuit.
What are the uses of electromagnets?
What is an electric fuse made up of?
What are the factors affecting heating effect of electric current?
______ wire is used in the filament of the bulbs.
An electric fuse is a wire made up of a material having ______ melting point.
An electrochemical cell converts ______ energy into ______ energy.
A trip switch is a ______ safety device.
Tara, after completing her exams, went to her grandmother's house along with her younger brother Rahul. One day, Rahul came home after playing and switched on the fan and air conditioner. At the same time, his grandmother was preparing a milkshake for him using a mixer. Suddenly, they heard a big sound and the electricity of the house got shut down. Tara is called an electrician. He said the main reason for supply to shut down was overloading.
- What is overloading?
- Is overloading and short the same? When does short-circuiting take place?
- How can the effects of overloading be avoided?
In the electric equipment producing heat like iron, electric heater, boiler, toaster etc., an alloy such as nichrome is used, not pure metals.
