The silver coating on the inner bottle prevents heat transfer by radiation, and the vacuum between its double wall prevents heat moving by convection. The thinness of the glass walls stops heat entering or leaving the flask by conduction.
Answer:
(a) 21.36 ohms
(b) 5.62 A
Explanation:
Parameters given:
Potential difference, V = 120 V
Power, P = 674 W
(a) Power is given as:
P = V²/R
Where R is resistance
=> R = V²/P
R = 120²/674
R = 14400/674
R = 21.36 ohms
(b) Power is also given as:
P = I*V
Where I = Current (time rate of flow of Electric charge)
=> I = P/V
I = 674/120
I = 5.62 A
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