Electricity And Magnetism - Study Mode

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[#276] What is the difference between a CFL and an LED Lamp? 1. To produce light, a CFL uses mercury vapour and phosphor while an LED lamp uses semi-conductor material. 2. The average life span of a CFL is much longer than of an LED lamp. 3. A CFL is less energy efficient as compared to an LED lamp. Which of the statements given above is/are correct?

(A) Only 1

(B) Only 2 and 3

(C) Only 1 and 3

(D) 1, 2 and 3

Correct Answer

(C) Only 1 and 3

[#277] When electrical energy is converted into motion

(A) There is no heat loss

(B) Heat loss is 50%

(C) Heat loss is 30%

(D) Heat loss is 80%

Correct Answer

(A) There is no heat loss

[#278] How much work is done in moving a charge of 5C across two points having a potential difference of 17V:

(A) 75 J

(B) 40 J

(C) 85 J

(D) 45 J

Correct Answer

(C) 85 J

[#279] The resistivity of an electric conductor depends on:

(A) Area of cross section

(B) All given options

(C) Length

(D) Material

Correct Answer

(D) Material

[#280] An electric iron of 1250 W is used 3 h per day. The amount of energy used by that electric iron in a day will be . . . . . . . . . units.

(A) 0.375

(B) 375

(C) 37.5

(D) 3.75

Correct Answer

(D) 3.75