Electricity: Class 10 Science Q&A · Page 3
281 free answers on Electricity (Science) for Class 10 students, across CBSE, ICSE and State boards.
Question & Answer
Questions
- ScienceClass 10CBSE
1. Electrical resistivity of a given metallic wire depends upon (a) its length (b) its thickness (c) its shape nature of the material
Soln: Answer is (d) nature of the material
- ScienceClass 10ICSE
Which electric heating devices in your home do you think have resistors which control the flow of electricity?
Following are the electric heating devices that have resistors that control the flow of electricity: Electric iron Room heater Water heater Electric oven
- ScienceClass 10ICSE
An electric iron is connected to the mains power supply of 220V. When the electric iron is adjusted at ‘minimum heating’ it consumes a power of 360W but at ‘maximum heating’ it takes a power of 840W. Calculate the current and resistance in each case.
Given, V = 220V Pmin = 360W Pmax = 840 W When the heating is minimum, Pmin = VI 360 = I220 I = 1.63amp R = V/I R = 200/1.63 R = 134.96 ohms When the heating is maximum, Pmax = VI 840 = 220I I = 3.81amp R = V/I R = 220/3.81 R = 57.74 ohms
- ScienceClass 10ICSE
Two exactly similar heating resistances are connected in series and 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.
When the heating resistances are connected in series more heat is obtained per minute. This is because the total resistance in series combination is more when compared to the total resistance in parallel combination.
- ScienceClass 10ICSE
How does the wire in the filament of a light bulb behave differently to the other wires in the circuit when the current flows? b) What property of the filament wire accounts for this difference?
The behavior of the wire in the filament of a light bulb is different from the other wires of the circuit as the wire used in the filament becomes white hot while the other wires do not heat much. The high resistance of the filament wire is responsible for the difference seen between the filament wire and the other wires of the circuit.
- ScienceClass 10ICSE
The electrical resistivities of four materials P, Q, R, and S are given below: P: 6.84 × 10-8Ωm Q: 1.70 × 10-8Ωm R: 1.0 × 1015Ωm S: 11.0 × 10-7Ωm 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.
The heating element of an electric iron is S because the resistivity of S is This material is nichrome. The connecting wires of an electric iron is Q as it has low This material is copper. The covering of connecting wires is R as the resistivity of R is very high and the material is
- ScienceClass 10ICSE
If the current flowing through a fixed resistor is halved, the heat produced in it will becomes: a) double b) one-half c) one-fourth four times
The correct option is: c) four times When the current flowing through a fixed resistor is halved, then the heat produced in the resistor will becomes four times the actual value.
- ScienceClass 10ICSE
Which of the following is the most likely temperature of the filament of an electric light bulb when it is working on the normal 220V supply line? a) 500°C b) 1500°C c) 2500°C d) 4500°C
The correct option is c) 2500°C
- ScienceClass 10ICSE
In a filament types light bulb, most of the electric power consumed appears as: a) visible light b) infrared rays c) ultraviolet rays fluorescent light
The correct option is b) infrared rays The electric power consumed in a filament type light bulb is an infrared rays
- ScienceClass 10ICSE
Which of the following characteristics is not suitable for a fuse wire? a) thin and short b) thick and short c) low melting point higher resistance than rest of wiring
The correct option is b) thick and short When a fuse wire is thick the electrons available are more which is not a suitable characteristic of a fuse wire.
- ScienceClass 10ICSE
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 y × z × x
The correct option is b) x × z × y2
- ScienceClass 10ICSE
The elements of electric heating devices are usually made of: a) tungsten b) bronze c) nichrome argon
The correct option is c) nichrome The elements of an electric heating devices are made using nichrome.
- ScienceClass 10ICSE
An electric fuse works on the: a) chemical effect of current b) magnetic effect of current c) lighting effect of current heating effect of current
The correct option is d) heating effect of current Heating effect of current is the working principle for an electric fuse.
- ScienceClass 10ICSE
The current passing through an electric kettle has been doubled. The heat produced will becomes: a) half b) double c) four times one-fourth
The correct option is c) four times The heat produced in an electric kettle becomes four times the actual value when the current is doubled.
- ScienceClass 10ICSE
The heat produced by passing an electric current through a fixed resistor is proportional to the square of: a) magnitude of resistance of the resistor b) temperature of the resistor c) magnitude of current time for which current is passed
The correct option is c) magnitude of current The heat produced by passing an electric current through a fixed resistor is proportional to the square of the magnitude of current.
- ScienceClass 10ICSE
Derive the expression for the heat produced due to a current I flowing for a time interval t through a resistor R having a potential difference V across its ends. With which name is this relation known? b) How much heat will an instrument of 12W produce in one minute if it is connected to a battery of 12V? c) The current passing through a room heater has been halved. What will happen to the heat produced by it? d) What is meant by the heating effect of current? Give two applications of the heating effect of current. Name the material which is used for making the filaments of an electric bulb.
When an electric charge Q moves against the potential difference V then the amount of work done is given as: W = Q × V (1) We know, current I = Q/T Q = IT (2) By Ohm’s law, V/I = R V = IR (3) Substituting the equation (2) and (3) in (1), we get W = I2RT Assumption: The electrical work done is converted into heat energy Therefore, heat produced is H = I2RT The above equation is known as Joule’s law of he
- ScienceClass 10ICSE
100 joules of heat is produced per second in a 4ohm resistor. What is the potential difference across the resistor?
H = 100J T = 1s R = 4ohms We know that, H = I2RT 100 = I2 x 4 x 1 100/4 = I2 I = 5amp V = IR V = 5 x 4 V = 20V
- ScienceClass 10ICSE
A resistance of 25Ω is connected to a 12V battery. Calculate the heat energy in joules generated per minute.
Given, R = 25Ω V = 12V T = 60s H = ? V = IR 12 = 25I I = 0.48amp We know that, H = I2RT H = 345.6J
- ScienceClass 10ICSE
An electric heater of resistance 8Ω takes a current of 15A from the mains supply line. Calculate the rate at which heat is developed in the heater.
Given, R = 8ohm I = 15amp T =1s We know that, H = I2RT H = 1800J/s
- ScienceClass 10ICSE
A heating coil has a resistance of 200Ω. At what rate will heat be produced in it when a current of 2.5A flows through it?
Given, R = 200 ohms I = 2.5amp T = 1s We know that, H = I2RT H = 1250J/s