CBSE Class 10 Science: Chapter 12 Electricity VSA Questions (with Answers)
Welcome to Part 2 of our 8-part series on Chapter 12, Electricity. This post provides a collection of Very Short Answer (VSA) questions, each worth 1 mark, as per the latest CBSE pattern. These are perfect for quick revision and checking your fundamental understanding.
Part 2: Very Short Answer (VSA) Questions
Define the SI unit of electric current.
The SI unit of electric current is the Ampere (A). One ampere is defined as the flow of one coulomb of charge per second (1 A = 1 C/s).
What is the SI unit of potential difference?
The SI unit of potential difference is the Volt (V).
State Ohm's Law.
Ohm's Law states that the potential difference (V) across a metallic conductor is directly proportional to the current (I) flowing through it, provided its temperature remains constant. (V ∝ I)
Define 1 Volt.
The potential difference between two points is said to be 1 Volt if 1 Joule of work is done in moving 1 Coulomb of charge from one point to the other (1 V = 1 J/C).
Name the device that helps to maintain a potential difference across a conductor.
A cell or a battery.
What is the SI unit of electrical resistivity?
Ohm-meter (Ω m).
Related Posts
Why are alloys like Nichrome used in heating devices?
Because they have high resistivity and a high melting point, and they do not oxidize (burn) easily at high temperatures.
How is a voltmeter connected in a circuit?
A voltmeter is always connected in parallel across the component whose potential difference is to be measured.
How is an ammeter connected in a circuit?
An ammeter is always connected in series in the circuit to measure the current flowing through it.
List the factors on which the resistance of a conductor depends.
Resistance depends on: (i) length of the conductor, (ii) area of cross-section, (iii) nature of the material, and (iv) temperature.
Define electric power. What is its SI unit?
Electric power is the rate at which electrical energy is consumed or dissipated in an electric circuit. Its SI unit is the Watt (W).
What is the commercial unit of electrical energy?
Kilowatt-hour (kWh), also known as a 'unit'.
State Joule's Law of Heating.
It states that the heat produced (H) in a resistor is directly proportional to (i) the square of the current (I²), (ii) the resistance (R), and (iii) the time (t) for which the current flows. (H = I²Rt).
Why is tungsten used almost exclusively for the filament of electric bulbs?
Because it has a very high melting point (approx 3380 °C) and becomes incandescent (emits light) at a high temperature without melting.
What is an electric circuit?
A continuous and closed path along which an electric current can flow is called an electric circuit.
How many joules are in one kilowatt-hour?
1 kWh = 3.6 × 10⁶ Joules.
A wire of resistance R is cut into two equal parts. What is the resistance of each part?
R/2.
Resistance is directly proportional to length (R ∝ L). When the length is halved, the resistance is also halved.
What happens to the current in a circuit if the resistance is doubled, keeping the potential difference the same?
The current becomes half.
According to Ohm's Law (I = V/R), current (I) is inversely proportional to resistance (R). If R is doubled, I becomes I/2.
Why does the cord of an electric heater not glow while the heating element does?
The heating element is made of an alloy (like Nichrome) with very high resistance, while the cord is made of a material (like copper) with very low resistance. Since Heat ∝ R, the element glows but the cord does not.
What is the resistance of an ideal ammeter?
Zero.
An ideal ammeter should have zero resistance so that it does not change the total resistance or current of the circuit it is measuring.
What is the resistance of an ideal voltmeter?
Infinite.
An ideal voltmeter has infinite resistance so that it draws no current from the circuit when connected in parallel.
What remains constant in a series combination of resistors?
Electric current.
What remains constant in a parallel combination of resistors?
Potential difference (voltage).
What is a rheostat?
A rheostat is a component used in a circuit to provide a variable resistance, which can be used to control the current.
A charge of 60 C passes through an electric lamp in 2 minutes. What is the current in the lamp?
The current is 0.5 A.
Given: Q = 60 C, t = 2 minutes = 120 seconds.
We know, I = Q/t
I = 60 C / 120 s = 0.5 A.
