VBQs Class 10 Science Electricity

Please refer to VBQs for Class 10 Science Electricity. All value based questions for English Class 10 have been provided with solutions. We have provided below important values questions and answers. Students should learn these solved VBQs for Class 10 Science as these will help them to gain more marks and help improve understanding of important topics.

Electricity VBQs Class 10 Science with Answers

Multiple Choice Questions

Question. Electrical resistivity of any given metallic wire depends upon
(a) its thickness
(b) its shape
(c) nature of the material
(d) its length

Question. When electric current is passed, electrons move from:
(a) high potential to low potential.
(b) low potential to high potential.
(c) in the direction of the current.
(d) against the direction of the current.

Question. The heating element of an electric iron is made up of:
(a) copper
(b) nichrome
(c) aluminium
(d) iron

Question. What is the commercial unit of electrical energy?
(a) Joules
(b) Kilojoules
(c) Kilowatt-hour
(d) Watt-hour

Question. In an electrical circuit two resistors of 2 Ω and 4 Ω respectively are connected in series to a 6 V battery. The heat dissipated by the 4 Ω resistor in 5 s will be
(a) 5 J
(b) 10 J
(c) 20 J
(d) 30 J

Question. A student carries out an experiment and plots the V-I graph of three samples of nichrome wire with resistances R₁ R₂ and R₃ respectively. Which of the following is true?

(a) R₁ = R₂ = R₃
(b) R₁ > R₂ > R₃
(c) R₃ > R₂ > R₁
(d) R₂ > R₃ > R₁

Question. Work of 14 J is done to move 2 C charge between two points on a conducting wire. What is the potential difference between the two points?
(a) 28 V
(b) 14 V
(c) 7 V
(d) 3.5 V

Question. Coulomb is the SI unit of:
(a)charge
(b) current
(c) potential difference
(d) resistance

Question. If R1 and R2 be the resistance of the filament of 40 W and 60 W, respectively operating 220 V, then
(a) R1 < R2
(b) R2 < R1
(c) R1 = R2
(d) R1 ≥ R2

Question. Calculate the current flow through the 10 Ω resistor in the following circuit.

(a) 1.2 A
(b) 0.6 A
(c) 0.2 A
(d) 2.0 A

Question. The resistance of a wire of length 300 m and cross-section area, 1.0 mm² made of material of resistivity 1.0 x 10⁻⁷ Ω is:
(a). 2 Ω
(b). 3 Ω
(c). 20 Ω
(d). 30 Ω

Question. Two resistors connected in series give an equivalent resistance of 10 Ω. When connected in parallel, give 2.4 Ω. Then the individual resistance is
(a) each of 5 Ω
(b) 6 Ω and 4 Ω
(c) 7 Ω and 4 Ω
(d) 8 Ω and 2 Ω

Case Study Based Questions

In the given circuit, three identical bulbs B1, B2 and B3 are connected in parallel with a battery of 4.5 V. Study the diagram and answer the questions given below :

Question. What will happen to the other two bulbs if the bulb B3 gets fused ?
(A) They will also stop glowing.
(B) Other bulbs will glow with same brightness.
(C) They will glow with low brightness.
(D) They glow with more brightness.

Question. If the wattage of each bulb is 1.5 W, how much readings will the ammeter A show when all the three bulbs glow simultaneously?
(A) 1.0 A
(B) 2 A
(C) 1.5 A
(D) None of the above

Question. Find the total resistance of the circuit.
(A) 1.0 Ω
(B) 4.5 Ω
(C) 1.5 Ω
(D) 2.0 Ω

Question. How many resistors of 88 Ω are connected in parallel to carry 10 A current on a 220 V line ?
(A) 2 resistors
(B) 1 resistors
(C) 3 resistors
(D) 4 resistors

Short Answer Type Questions

Question. Calculate the number of electrons that would flow per second through the cross- section of a wire when 1 A current flows in it.
Answer. Given: I = 1A , t = 1 s
Q = It , Q =1Ax 1s = 1C
But Q = ne or n = Q/e = 1 /1.6×10-19 = 6.25 x 108 electrons

Question. How much work is done in moving a charge of magnitude 3 C across two points having a potential difference of 12 V?
Answer. Given : Q = 3 C, V = 12 V
To find: W
V = W/Q
W = VQ = 12 × 3 = 36 J

Question. Keeping the potential difference constant, the resistance of a circuit is doubled. By how much does the current change?
Answer: V = IR
V/R= l
Since the resistance and the current are inversely proportional, the current will become half.

Question. Give reason for the following:
a. Tungsten used almost exclusively for filament of electric lamp.
b. Why do we use copper and aluminium wires for transmission of electric current?
Answer. a. Tungsten is used in making the filament of electric lamp because it has high resistivity and high melting point.
b. The copper and aluminium have low resistivity and high conductivity.

Question. List in a tabular form two differences between a voltmeter and an ammeter.
Answer.

Question. Define electric power. Write an expression relating electric power, potential difference and resistance.
Answer. Electric power : It is the amount of electric energy consumed in a circuit per unit time.
Expression :
P = V2 /R Where, P = Electric Power, V = Potential difference, R = Resistance

Long Answer Type Questions

Question. (a) List the factors on which the resistance of a conductor in the shape of a wire depends.
(b) Why are metals good conductors of electricity whereas glass is a bad conductor of electricity? Give reason.
(c) Why are alloys commonly used in electrical heating devices? Give reason.
Answer. a. Factors on which resistance of a wire depends:
i. Resistance is directly proportional to length (l)
ii. Resistance is inversely proportional to area of cross-section(A).
R α l , R α 1/A
R α l/A
or R = ρ l/A, here ρ is the resistivity of the material at a particular temperature
(ie, resistivity depends on material and temperature)
b. Metals are good conductors due to having large number of free electrons and their low resistivity. Glass is a bad conductor because it has no free electrons and its resistivity is higher.
c. Alloys are commonly used in electrical heating devices due to their high resistivity and high melting point .
Question. A nichrome wire has a resistance of 10 Ω. Find the resistance of another nichrome wire, whose length is three times and area of cross-section four times the first wire.
Answer. we have resistance R = ρ l/A
For first wire length L1= l, Area of cross section A1= A
So for first wire resistance R1= ρ l/A = 10 Ω
For second wire length L2 = 3l , Area of cross section A2 = 4A
So for second wire resistance R2 = ρ 3l/4A

Question. State the formula co-relating the electric current flowing in a conductor and the voltage applied across it. Also, show this relationship by drawing a graph. What would be the resistance of a conductor, if the current flowing through it is 0.35 ampere when the potential difference across it is 1.4 volt?
Answer. potential difference V = IR where I is electric current and R, resistance of conductor ie, V α l
If we plot a graph b/w V and I , it is a straight line.
Graph b/w V and I :

Given current l = 0.35 A , potential difference V = 1.4 V

Question. Calculate the total cost of running the following electrical devices in the month of September, if the rate of 1 unit of electricity is Rs. 6.00. (i) Electric heater of 1000 W for 5 hours daily. (ii) Electric refrigerator of 400 W for 10 hours daily 
Answer. P₁ = 1000 W = 1kW, t₁= 5h,
P2 = 400 W = 400 /1000 kW = 0.4KW , t2 = 10h
No. of days, n = 30
E₁ =P₁ × t₁ × n = 1 kW × 5h × 30 = 150 kWh
E₂ =P₂ × t₂ × n = 0.4kW x 10h x 30 = 120kWh
Total energy = (150 + 120) kWh = 270 kWh
Total cost = 270 x 6 = Rs. 1620/-