(a) 1:2 (b) 2:1 (c) 1:4 (d) 4:1 Answer: Each R, series ( R_s = 2R ), parallel ( R_p = R/2 ) Heat ( H = V^2 t / R ) → ( H_s / H_p = R_p / R_s = (R/2) / (2R) = 1/4 ) → (c)
Answer: ( R = \rho l / A ) → ( l = R A / \rho ) ( A = \pi (0.25 \times 10^{-3})^2 = \pi \times 6.25 \times 10^{-8} ) ( l = (10 \times \pi \times 6.25 \times 10^{-8}) / (1.6 \times 10^{-8}) ) ( l \approx 122.7 , \text{m} ) If diameter doubled, area 4× → resistance becomes 1/4 → 2.5 Ω.
I’ll provide answers to the and the exercise questions at the end of the chapter. In-Text Questions (Page 200) Q1. What does an electric circuit mean? Answer: An electric circuit is a continuous and closed path for the flow of electric current, consisting of a source of electricity (like a cell or battery), connecting wires, a switch, and a device (like a bulb). class 10 electricity ncert solutions
Answer: Alloys have higher resistivity and do not oxidize easily at high temperatures.
Answer: ( H = I^2 R t = 5^2 \times 20 \times 30 = 25 \times 20 \times 30 = 15000 , \text{J} ) In-Text Questions (Page 220) Q1. What determines the rate at which energy is delivered by a current? Answer: Electric power ( P = V \times I = I^2 R = V^2 / R ) (a) 1:2 (b) 2:1 (c) 1:4 (d) 4:1
Answer: ( R = V/I = 12 / (2.5 \times 10^{-3}) = 4800 , \Omega )
Answer: Total R = 0.2+0.3+0.4+0.5+12 = 13.4 Ω ( I = 9 / 13.4 \approx 0.67 , \text{A} ) (same in series) What does an electric circuit mean
Answer: From Ohm’s law ( V = IR ), if ( R ) constant and ( V ) becomes half, ( I ) also becomes half.
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