Electricity: Class 10 Science Q&A · Page 8
281 free answers on Electricity (Science) for Class 10 students, across CBSE, ICSE and State boards.
Question & Answer
Questions
- ScienceClass 10ICSE
Give the law of combination of resistances in series.
The law of combination of resistances in series states that the combined resistance of any number of resistance that are connected in series is equal to the individual resistances.
- ScienceClass 10ICSE
The electrical resistivities of five substances A, B, C, S, and E are given below: A = 5.20×10-8 Ωm B = 110×10-8 Ωm C = 2.60×10-8 Ωm D = 10.0×10-8 Ωm E = 1.70×10-8 Ωm a) Which substance is the best conductor of electricity? Why? b) Which one is a better conductor: A or C? Why? c) Which substance would you advice to be used for making heating elements of electric irons? Why? Which two substances should be used for making electric wires? Why?
E is the best conductor of electricity because it has the least resistivity C is a better conductor between A and C because the resistivity of C is lesser than that of A B can be used in the making of the heating elements of an electric iron because the resistivity of B is the highest C and E are the two substances that should be used for making electric wires because they have low electrical resistivities
- ScienceClass 10ICSE
The electrical resistivities of four materials A, B, C, and D are given below: A = 110×10-8 Ωm B = 1.0×1010 Ωm C = 10.0×10-8 Ωm D = 2.3×103 Ωm Which material is: a) Good conductor b) Resistor c) Insulator d) Semiconductor Answer:
Good conductor is C = 10.0×10-8 Ωm Resistor is A = 110×10-8 Ωm Insulator is B = 0×1010 Ωm Semiconductor is D = 3×103 Ωm
- ScienceClass 10ICSE
The electrical resistivities of three materials P, Q, and R are given below: P = 2.3×103 Ωm Q = 2.63×10-8 Ωm R = 1.0×1015 Ωm Which material will you use for making? a) Electric wires b) Handle for soldering iron c) Solar cells Give reasons for your choices.
For making of the electric wires, Q = 63×10-8 Ωm can be used as this material has a very low resistivity For making of the handle for soldering iron, R = 0×1015 Ωm can be used as this has a very high resistivity For making of the solar cells, P = 3×103 Ωm can be used as this materials is a semiconductor
- ScienceClass 10ICSE
A piece of wire of resistance 20Ω is drawn out so that its length is increased to twice its original length. Calculate the resistance of the wire in the new situation.
We know that, R = ρl/A Given that, l’ = 2l A’ = A/2 And ρ’ = ρ (as the material of the wire is the same) Therefore, R’ = ρ’l’/A’ = ρ2l/(A/2) = 4ρl/A = 4R Therefore, R’ = 4×20 = 80Ω
- ScienceClass 10ICSE
If the area of cross-section of a resistance wire is halved, then its resistance becomes: a) One-half b) 2 times c) One-fourth 4 times
The correct option is b) 2 times.
- ScienceClass 10ICSE
The resistivity of copper metal depends on only one of the following factors. This factor is: a) Length b) Thickness c) Temperature Area of cross-section
The correct option is c) Temperature
- ScienceClass 10ICSE
When the area of cross-section of a conductor is doubled, its resistance becomes: a) Double b) Half c) Four times One-fourth
The correct option is b) half
- ScienceClass 10ICSE
The resistivity of a certain material is 0.6 Ωm. The material is most likely to be: a) An insulator b) A superconductor c) A conductor A semiconductor
The correct option is d) A semiconductor
- ScienceClass 10ICSE
If the diameter of a resistance wire is halved, then its resistance becomes: a) Four times b) Half c) One-fourth Two times
The correct option is a) four times. When the diameter of a resistance wire is halved, the resistance becomes four times.
- ScienceClass 10ICSE
If the resistance of a certain copper wire is 1Ω, then the resistance of a similar nichrome wire will be about: a) 25 Ω b) 30 Ω c) 60 Ω d) 45 Ω
The correct option is c) 60 Ω. The resistance of nichrome is 60 Ω when the resistance of a copper wire is 1 Ω.
- ScienceClass 10ICSE
When the diameter of a wire is doubled, its resistance becomes: a) Double b) Four times c) One-half One-fourth
The correct option is d) one-fourth We know that R = ρl/A Therefore, when the diameter of the wire is doubled, the resistance becomes one-fourth of the actual value.
- ScienceClass 10ICSE
The resistance of a wire of length 300m and cross-section area 1.0mm2 made of material of resistivity 1.0×10-7 Ωm is: a) 2Ω b) 3Ω c) 20Ω d) 30Ω
The correct option is d) 30Ω We know that R = ρl/A Substituting the values in the above equation we get 30Ω.
- ScienceClass 10ICSE
Define resistivity. Write an expression for the resistivity of a substance. Give the meaning of each symbol. b) State the SI unit of resistivity. c) Distinguish between resistance and resistivity. d) Name two factors on which the resistivity of a substance depends and two factors on which it does not depend. e) The resistance of a metal wire of length 1m is 26Ω at 20⸰C. if the diameter of the wire is 0.3mn, what will be the resistivity of the metal at that temperature? Answer:
Resistivity is defined as: ρ = R×A/l where, R is the resistance of the conductor A is the cross-sectional area of the conductor l is the length of the conductor The SI unit of resistivity is Ohm-meter Following are the differences between resistance and resistivity: Resistance Resistivity
- ScienceClass 10ICSE
Calculate the area of cross-section of a wire if its length is 1.0m, its resistance is 23Ω, and the resistivity of the material of the wire is 1.84×10-6Ωm.
Given, l = 1.0m R = 23 ohm ρ = 1.84×10-6Ωm We have, R = ρl/A 23 = 1.84×10-6 × 1/A A = 8×10-8 m2
- ScienceClass 10ICSE
How does the resistance of a wire change when: a) its length is tripled? b) its diameter is tripled? its material is changed to one whose resistivity is three times?
We know that, R = ρl/A l becomes 3l R’ = ρ3l/A = 3R Therefore, resistance gets tripled d becomes 3d R = ρl/A R = ρl/πr2 = ρl/π(d/2)2 R’ = R/9 Therefore, resistance becomes 1/9th ρ = 3ρ R’ = 3ρl/A = 3R Therefore, resistance becomes 3 times.
- ScienceClass 10ICSE
How does the resistance of a wire vary with its: a) area of cross-section? diameter?
When the resistance of a wire is varied, the area of cross-section increases, thereby reducing the resistance When the resistance of a wire is varied, the diameter of the material is increased, thereby reducing the resistance
- ScienceClass 10ICSE
What would be the effect on the resistance of a metal wire of: a) increasing its length b) increasing its diameter increasing its temperature
Following are the effects on the resistance of a metal wire when: As the length is increased, the resistance will increase As the diameter is increased, the resistance will decrease As the temperature is increased, the resistance will increase
- ScienceClass 10ICSE
Give one example to show how the resistance depends on the nature of material of the conductor b) Calculate the resistance of an aluminum cable of length 10km and diameter 2.0mm if the resistivity of aluminum is 2.7×10-8Ωm.
Let us consider two wires with same length and Let these two wires be of copper metal and nichrome alloy. We know that the resistance of nichrome wire is 60 times more than that of the copper wire. Therefore, it is understood that the resistance depends on the nature of the material used in the conductor. Given, l = 10km = 10000m d = 2mm r = 1mm = 10-3m ρ = 2.7×10-8Ωm We know that, R = ρl/A Substituting the va
- ScienceClass 10ICSE
How does the resistance of a conductor depend on: a) length of the conductor b) area of cross-section of the conductor temperature of the conductor
Answer: Resistance of a conductor is dependent on the length of the As the length of the material increases, the resistance of the material decreases and vice versa. Resistance of a conductor is dependent on the area of cross-section of the As the cross-section area increases, the resistance of the material decreases and vice versa. As the temperature increases, the resistance of the material also