Electricity: Class 10 Science Q&A · Page 4
281 free answers on Electricity (Science) for Class 10 students, across CBSE, ICSE and State boards.
Question & Answer
Questions
- ScienceClass 10ICSE
When a current of 4amp passes through a certain resistor for 10 minutes, 2.88 × 104 J of heat are produced. Calculate a) the power of the resistor the voltage across the resistor
Given, I = 4amp T = 10min = 600s H = 2.88 × 104 J We know that, H = I2RT 28800 = 42×600R R = 3 ohms We know that, P = I2R P = 48W We know that, V = IR V = 12V
- ScienceClass 10ICSE
Explain why, the current that makes the heater element very hot, only slightly warms the connecting wires leading to the heater.
The connecting wires leading to the heater are slightly warmer than the wires that makes the heater element hot because they have low resistance which results in flow of negligible heat production in them.
- ScienceClass 10ICSE
Explain why, tungsten is used for making the filaments of an electric bulb.
Tungsten is used for the making of the filaments of an electric bulb because the melting point of the tungsten is very high. This means that the filament remains burning hot but won’t melt. The other reason for using tungsten is that it is flexible and the rate of evaporation is low at high temperatures.
- ScienceClass 10ICSE
Why is an electric bulb not filled with air? Explain why argon or nitrogen is filled in an electric bulb.
An electric bulb is not filled with air because the filament in an electric bulb is made using tungsten which would burn quickly when it comes in contact with the oxygen in the air. This is the reason why unreactive gases such as argon and nitrogen is used for filling an electric bulb. These gases are chemically unreactive.
- ScienceClass 10ICSE
State three factors on which the heat produced by an electric current depends. How does it depend on these factors?
Following are the three factors on which the heat produced by an electric current depend: Heat produced is directly proportional to the square of current Heat produced is directly proportional to resistance Heat produced is directly proportional to the time for which the current flows
- ScienceClass 10ICSE
Write down the formula for the heat produced when a current I is passed through a resistor R for time t. b) An electric iron of resistance 20 ohms draws a current of 5 amperes. Calculate the heat produced in 30 seconds.
Following is the formula for the heat produced: H = I2Rt Given, R = 20Ω I = 5amp t = 30s We know that, H = I2Rt Substituting the values we get, H = 15000J
- ScienceClass 10ICSE
Why does the connecting cord of an electric heater not glow hot while the heating element does?
The connecting cord of an electric heater does not glow hot while the heating element does because the connecting cord is made from copper which does not glow as the heat produced is negligible. Whereas in a heating element is made from the nichrome glows because a large amount of heat is produced when the current is passed through it.
- ScienceClass 10ICSE
Explain why, filament type electric bulbs are not power efficient.
Filament type electric bulbs are not power efficient because they consume most of the electric power as heat and a very small amount of electric power is converted into light.
- ScienceClass 10ICSE
Name two gases which are filled in filament type electric light bulbs.
Following are the two gases that are filled in filament type electric light bulbs: Argon Nitrogen
- ScienceClass 10ICSE
Name two devices which work on the heating effect of electric current.
Following are the two devices that work on the heating effect of an electric current: Electric heater Electric fuse
- ScienceClass 10ICSE
Which effect of current is utilized in the working of an electric fuse?
The heating effect of current is utilized in the working of an electric fuse.
- ScienceClass 10ICSE
Which effect of current is utilized in an electric light bulb?
The heating effect of current is utilized in an electric light bulb.
- ScienceClass 10ICSE
Name two effects produced by electric current.
Following are the two effects produced by electric current: Heating effect Magnetic effect
- ScienceClass 10ICSE
If the current passing through a conductor is doubled, what will be the change in heat produced?
When the current passing through a conductor is doubled, the heat produced will increase by four times. This is because the heat produced is directly proportional to the square of current.
- ScienceClass 10ICSE
How does the heat H produced by a current passing through a fixed resistance wire depend on the magnitude of current I?
The heat H produced by a current passing through a fixed resistance wire is directly proportional to the magnitude of the current I.
- ScienceClass 10ICSE
If the potential difference between the ends of a fixed resistor is halved, the electric power will becomes: a) double b) half c) four times one-fourth
The correct option is d) one-fourth When the potential difference between the ends of a fixed resistor is halved, the electric power becomes one- fourth of the actual value.
- ScienceClass 10ICSE
At a given time, a house is supplied with 100A at 220V. How many 75W, 220V light bulbs could be switched on in the house at the same times if they are all connected in parallel? a) 93 b) 193 c) 293 d) 393
The correct option is c) 293 A total of 293 bulbs can be used when they are all connected in parallel and have 75W and 220V.
- ScienceClass 10ICSE
How many joules of electrical energy are transferred per second by a 6V, 0.5A lamp? a) 30 J/s b) 12 J/s c) 0.83 J/s 3 J/s
The correct option is d) 3 J/s When 6V and 0.5A lamp is used, 3 J/s electrical energy is required.
- ScienceClass 10ICSE
An electric kettle for use on a 230V supply is rated at 3000W. For safe working, the cable connected to it should be able to carry at least: a) 2A b) 5A c) 10A d) 15A
The correct option is d) 15A 15A current is required for the safe working of an electric kettle that has a supply of 230V.
- ScienceClass 10ICSE
How much energy is does a 100W electric bulb transfer in 1 minutes? a) 100J b) 600J c) 3600J d) 6000J
The correct option is d) 6000J 6000J of energy is transferred in an electric bulb with a power of 100W in 1 minute.