Question

0158 100 W heater is used to heat 500 g of water from 20C to 50C. How long should the heater be switched on? Specific heat capacity of water is 4.2 J/g0. A 63 sec B 63 min 630 sec D 6.3 min​

Answer 1

Answer:

Heat energy E=ms(T

2

−T

1

)

Heat required is E=900×50×(38−18)=900×10

3

J

So the time required by heater of power 500W to supply this amount of heat is

△t=

P

E

=

500

900×10

3

=1800 sec=30 min

Explanation:

hope it's helpful for u

Answer 2

Given info : 100W heater is used to heat 500g of water from 20°C to 50°C.

To find : how long should the heatr be switched on ?

solution : power of heater × time taken by heater to raise the temperature of water from 20°C to 50°C = msΔT

here m = mass of water = 500g

s = specific heat capacity of water = 4.2 J/g/°C

ΔT = change in the temperature = 50°C - 20°C = 30°C

⇒ 100 × t = 500 × 4.2 × 30

⇒ t = 630 sec

therefore the time required to raise the temperature of water is 630 sec. hence option (C) 630 sec , is correct.