Resistance of a metal wire of length 1 m is 26 Ω at 20 ° C . If the diameter of the wire is 0 . 3 mm , What will be the resistivity of the metal at that temperature?

The resistivity depends on the nature of the material of the conductor and also on temperature. The SI unit of resistivity is ohm metre. Here; length of the wire, l = 1 m The area of cross-section of the wire, A = π d 2 4 = 3 . 14 × 0 . 3 × 10 - 3 m 2 4 = 7 . 065 × 10 - 8 m 2 Resistance of the wire, R = 26 Ω The resistance is directly the length of the conductor, it is also inversely proportional to the area of cross-section of the conductor. Hence, R ∝ l A R = ρ l A Here ' ρ ' is the specific resistance or the resistivity of the conductor. ρ = R A l = 26 Ω × 7 . 065 × 10 - 8 m 2 1 m = 1 . 84 × 10 - 6 Ω m .

A current of 0 . 5 A is drawn by a filament of an electric bulb for 10 minutes. Find the amount of electric charge that flows through the circuit.

Given I = 0 . 5 A , t = 10 minutes Time(in seconds) = 10 × 60 = 600 s Net charge flow through the circuit Q = I × t Q = 0 . 5 × 600 Q = 300 C

What is the commercial unit of electrical energy? Which uses more 250 W TV set in one hour or a 1200 W electric iron in ten minutes and how?

The commercial unit of energy is Kilowatt-hour denoted by kWh . For T.V, Power (P) = 250 W Time (t) = 1 hr = 60 × 60 = 3600 s For toaster, Power = 1200 W Time = 10 min = 10 × 60 = 600 s E = P × T Energy consumed by the TV set = 250 × 3600 = 9 × 10 5 J Energy consumed by a toaster = 1200 × 600 = 7 . 2 × 10 5 J &there4; The energy consumed by a 250 W TV set in 1 hr is more than the energy consumed by a toaster of power 1200 W in 10 minutes.

E M B I B E

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR SCIENCE>Chapter 12 - Electricity>assam board-2019>Q 10

HARD

10th Assam Board

IMPORTANT

Earn 100

$400 J$ of heat is produced per second in a $4 Ω$ resistor. Calculate the potential difference across the resistor.

Important Questions on Electricity

EASY

10th Assam Board

IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR SCIENCE>Chapter 12 - Electricity>assam board-2020>Q 11

Which of the following terms does not represent electrical power in a circuit?

EASY

10th Assam Board

IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR SCIENCE>Chapter 12 - Electricity>assam board-2020>Q 12

A current of

0.6 A

is drawn by a filament of an electric bulb for

5

minutes. Find the amount of electric charge that flows through the circuit.

EASY

10th Assam Board

IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR SCIENCE>Chapter 12 - Electricity>assam board-2020>Q 13

How electrical charges flow inside a wire. Explain.

MEDIUM

10th Assam Board

IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR SCIENCE>Chapter 12 - Electricity>assam board-2020>Q 14

Write the S.I. unit of resistivity. An electric motor takes $5 A$ from a $220 V$ source. Determine the power of the motor and energy consumed in $2$ hours.

EASY

10th Assam Board

IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR SCIENCE>Chapter 12 - Electricity>assam board-2020>Q 15

What determines the rate at which energy is delivered by a current? An electric heater of resistance