Tamil Nadu SSLC (Class 10) Effects of Electric Current — practice questions — page 4

1. Write the two conditions from the data given. 2. Series gives $R_1 + R_2 = 9$. 3. Parallel gives $\dfrac{R_1 R_2}{R_1 + R_2} = 2$, so $R_1 R_2 = 2 \times 9 = 18$. 4. Now find two numbers that sum to 9 and have product 18; these are 3 and 6. 5. Check: parallel $= \dfrac{3\times6}{9} = 2\,\Omega$, series $= 9\,\Omega$, both match. 6. Trap B (4,5): sum 9 but product 20, so parallel would be 2.22, not 2. 7. Trap C (2,7): product 14 gives parallel 1.56; trap D (1,8): product 8 gives parallel 0.89. _Source: Samacheer Kalvi (TN SCERT) Class 10 Science, Unit 4 Electricity "Electricity", p.64_

1. Resistance is proportional to length for the same material and area. 2. Cutting into five equal parts makes each part one-fifth the original length. 3. So each part has resistance $R/5$. 4. Trap A (5R) would be five parts in series; trap C (R/25) is the parallel combination of all five. _Source: Samacheer Kalvi (TN SCERT) Class 10 Science, Unit 4 Electricity "Electricity", p.64_

1. The earth wire connects the metal body of an appliance to the ground. 2. If the live wire touches the metal body, the leakage current flows safely to earth. 3. This prevents the user from getting a dangerous shock. 4. It does not normally carry the working current or change the voltage. _Source: Samacheer Kalvi (TN SCERT) Class 10 Science, Unit 4 Electricity "Electricity", p.63_