List of top Science Questions on Electricity asked in CBSE Class X

(a) Study the given electric circuit in which 2 A electric current is flowing between points X and Y.

(i) Using the battery, key, voltmeter and ammeter in this given electric circuit, redraw a circuit diagram in which 2 \(\Omega\) and 4 \(\Omega\) resistors are connected between X and Y in parallel combination.
(ii) Circuit drawn by you, in which resistors are connected in parallel combination, calculate the electric current flowing through 4 \(\Omega\) resistor.
Why does an electric bulb become dim when an electric heater in parallel circuit is switched ON?
How to connect three resistors each of resistance 8 $\Omega$, so that the equivalent resistance of the combination is 12 $\Omega$? Draw diagram of the combination and justify your answer.
Derive the expression for the equivalent resistance of three resistors \( R_1 \), \( R_2 \) and \( R_3 \) connected in parallel combination.
Two lamps 'A' and 'B' of rating 50 W; 220 V and 100 W, 220 V are connected in series combination. Find out the ratio of the resistances (\(R_A : R_B\)) of these lamps.
(a) The resistance of a wire of 0.01 cm radius and 1.0 cm length is \( 7 \, \Omega \).
Calculate its resistivity.
OR
(b) An electric heater is rated 220 V; 11 A. Calculate the power consumed if the heater is operated at 200 V.
Three students Shweta, Ayesha and Samridhi were performing i an experiment to understand the factors on which the resistance of a conductor depends. Each one of them completed electric circuit with the help of a cell, an ammeter, a plug key and wire. Shweta put nichrome wire of length 7’ in the circuit and after plugging the key, noted current in the ammeter. Ayesha put nichrome wire of same thickness but twice the length i.e. ‘21’ in the circuit and after plugging the key, noted current in the ammeter. Samridhi took copper wire of length ‘I’ and same thickness in the circuit and after plugging the key, noted current in the ammeter.

(i) Study the diagram and name the parts marked as A, B, C, and D. 
(ii) Write the function of A and C.

 

Define the term "potential difference" between two points in an electric circuit carrying current. Name and define its S.I. unit. Also express it in terms of S.I. unit of work and charge.
What do the symbols given below represent in an electric circuit? Write one function of each.
Symbol of an Ammeter
Explain the statement "Potential difference between two points is 1 volt".
Assertion (A): Food web is a network of several food chains operating in an ecosystem.
Reason (R): Food web decreases the stability of an ecosystem.
Study the circuit shown in which two resistors X and Y of resistances 3 Ω and 6 Ω respectively are joined in series, with a battery of 2 V
two resistors X and Y of resistances 3 Ω and 6 Ω
In our houses we receive A.C. electric power of 220 V. In electric iron or electric heater cables having three wires with insulation of three different colours – red, black and green are used to draw current from the mains. What are these three different wires called? Name them colourwise. What is the potential difference between the red wire and the black wire? What is the role of the wire with green insulation in case of accidental leakage of electric current to the metallic body of an electrical appliance?
A piece of wire of resistance 'R' is cut lengthwise into three identical parts. These parts are then connected in parallel. If the equivalent resistance of this combination is \( R' \), then the value of \( R/R' \) is:
In a domestic circuit five LED bulbs are arranged as shown. The source voltage is 220 V and the power rating of each bulb is marked in the circuit diagram. Based on the following circuit diagram, answer the following questions:
domestic circuit

(a) State what happens when
(i) key K1 is closed.
(ii) key K2 is closed.
(b) Find the current drawn by the bulb B when it glows.
(c) Calculate
(i) the resistance of bulb B, and
(ii) total resistance of the combination of four bulbs B, C, D and E.
OR
(c) What would happen to the glow of all the bulbs in the circuit when keys K1 and K2 both are closed and the bulb C suddenly get fused ? Give reason to justify your answer.
In case of four wires of same material, the resistance will be minimum if the diameter and length of the wire respectively are
Two resistors of 1 Ω and 3 Ω are connected in parallel in a circuit. If a current of 1 ampere is flowing through the circuit, the current flowing through the 3 Ω resistor is:
An electrical heater of resistance 10 Ω draws a steady current of 5 A from the service mains for 2 hours. Find the power of this heater and the amount of energy consumed by the heater in kilowatt-hour.
Obtain an expression for the amount of heat produced in a conductor of resistance R when a steady current I flows through it for a time t.
The resistance of a metallic wire of 100 m is 20 \(\Omega\). If the radius of the wire is 5 mm, find the resistivity of the metal of the wire.
Write the relation between resistivity (\(\rho\)) and resistance (\(R\)) for a uniform metallic conductor of length (\(l\)) and area of cross-section (\(A\)). Use this relation to obtain the SI unit of resistivity.
For distant transmission of electric power, an alternating current (ac) is considered to be advantageous over direct current (dc). Why?
How is the type of current used in household supply different from the one given by dry cells or storage batteries?
How does an electric fuse prevent the circuit and the appliances from possible damage due to short circuiting or overloading?