CBSE Class 10 Physics - Electricity (1 Mark Based Questions and Answers) Part-1

Q1: By what other name is the unit joule/coulomb called ?

Q2: Which of the following statements correctly defines a volt ?

(a) a volt is a joule per ampere.

(b) a volt is a joule per coulomb.

Answer: (b) a volt is a joule per coulomb.

Q3: (a) What do the letters p.d. stand for ?

(b) Which device is used to measure p.d. ?

(a) p.d. stands for potential difference.

(b) Voltmeter is used to measure p.d.

Q4: What is meant by saying that the electric potential at a point is 1 volt ?

Answer : Electric potential at a point is 1 volt means 1 joule of work is done in moving 1 unit positive charge from infinity to that point.

Q5: How much work is done when one coulomb charge moves against a potential difference of 1 volt ?

Potential difference (V) = 1 V

Charge moved (Q) = 1C

Work done = V × Q = 1 × 1 = 1J

Q6: What is the SI unit of potential difference?

Q7: How much work is done in moving a charge of 2 C across two points having a potential difference of 12 V ?

V = 12 V,

Q = 2 C

W = V × Q

= 12 × 2

= 24 J

Q8: What is the unit of electric charge ?

Q9: Define one Coulomb.

Answer: One coulomb of charge is that quantity of charge which exerts a force of 9 × 10⁹ Newton on an equal charge is placed at a distance of 1 m from it.

OR

A body is said to have 1 Coulomb of charge if it has an excess or deficit of 6.25 × 10¹⁸ electrons

Q10: What is meant by conductors and insulators ? Give two examples of conductors and two of insulators.

Conductors: Those substances through which electricity can flow are known as conductors. E.g., Copper, silver etc.

Insulators: Those substances through which electricity cannot flow are known as insulators. E.g., Plastic, cotton etc.

Q11: Which of the following are conductors and which are insulators ?

Sulphur, Silver, Copper, Cotton, Aluminium, Air, Nichrome, Graphite, Paper, Porcelain, Mercury, Mica, Bakelite, Polythene, Manganin.

Conductor: Silver, Copper, Aluminum, Nichrome, Graphite, Mercury, Manganin

Insulators: Sulphur, Cotton, Air, Paper, Porcelain, Mica, Bakelite, Polythene

Q12: What do you understand by the term “electric potential” ?  What is the unit of electric potential?

Answer: The electric potential (or potential) at a point in an electric field is defined as the work done in moving a unit positive charge from infinity to that point.

Unit of electric potential is volt.

Q13: Define potential difference? What is the SI unit of potential difference?

Answer: Work done in bring a unit charge from one point to another is called potential difference.

SI unit of potential difference is volt(V).

Q14: Name a device that helps to measure the potential difference across a conductor.

Q15: What is the potential difference between the terminals of a battery if 250 joules of work is required to transfer 20 coulombs of charge from one terminal of battery to the other?

Answer: Given: Work done (W) = 250J, Charge moved (Q) = 20C.

∵ V = W/Q

= 250/20 = 12.5 V

Q16: How is a voltmeter connected in the circuit to measure the potential difference between two points.

Answer: Voltmeter is always connected in parallel across the two points where the potential difference is to be measured.

Q17: The atoms of copper contain electrons and the atoms of rubber also contain electrons. Then why does copper conduct electricity but rubber does not conduct electricity ?

Answer: Copper has free electrons that are loosely held by the nuclei of the atoms. These free electrons result in conduction of electricity.

The electrons present in rubber are strongly held by the nuclei of its atoms. So, rubber does not have free electrons to conduct electricity.

Q18: Define electric field.

Answer: An electric field is a region around a source of charge within which a unit charge experiences a force of attraction or repulsion.