Chapter 11

NCERT
Class 10
Science
Solutions
16. Which uses more energy, a 250 W TV set in 1 hr, or a 1200 W toaster in 10 minutes?

Question:

Which uses more energy, a 250 W TV set in 1 hr, or a 1200 W toaster in 10 minutes?

Answer:

In the T.V. set, P = 250 W

Time t = 1 hr

t = 60 × 60 seconds = 36000 sec

Electrical energy E1 = P × t

E1 = 250 × 3600

E1 = 900000 J

E1 = 9 x 105 J

In heater, P = 120 W

Time t = 10 min

t = 100 × 60 seconds

t = 600 sec

Electrical energy E2 = P × t

E2 = 120 × 600

E2 = 72000 J

E2 = 7.2 × 104 J

Since, E1 > E2

So, T.V. uses more energy.

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