Title Unit No. 7 Current Electricity (S.C) Google Drive (Youtube Students) By Sir Shahid.pdf ✅

CURRENT ELECTRICITY (UNIT-7) MDCAT www.youtube.com/physicswithshahid Q1. The current in a component is reduced uniformly from 100 mA to 20 mA over a period of 8.0 s. What is the charge that flows during this time? (A) 160 mC (B) 320 mC (C) 480 mC (D) 640 mC Q2. A wire carries a current of 2.0 amperes for 1.0 hour. How many electrons pass a point in the wire in this time? (A) 1.2 x 10-15 (B) 7.2 x 103 (C) 1.3 x 1019 (D) 4.5 x 1022 Q3. A copper wire of cross-sectional area 2.0 mm2 carries a current of 10 A. How many electrons pass through a given cross-section of the wire in one second? (A) 1 x 101 (B) 5x106 (C) 6.3x1019 (D) 3.1x1025 Q4. The current in the circuit is 4.8A. What is the rate of flow and the direction of flow of electrons through the resistor R? (A) 3 x 109 s -1 in direction X to Y (B) 6 x 1018 s -1 in direction X to Y (C) 3 x 1019 s -1 in direction Y to X (D) 6 x 1018s -1 in direction Y to X Q5. Four-point charges, each of charge Q, are placed on the edge of an insulating disc of radius r. The frequency of rotation of the disc is f. What is the equivalent electric current at the edge of the disc? (A) 4Qf (B) 4Q f (C) 8πrQf (D) 2Qf πr Q6. An electric current is passed from a thick copper wire through a section of thinner copper wire before entering a second thick copper wire as shown. Which statement about the current and the speed of electrons in the wires is correct? (A) The current and the speed of the electrons in the thinner wire are both less than in the thicker copper wires. (B) The current and the speed of the electrons is the same in all the wires. (C) The current is the same in all the wires but the speed of the electrons in the thinner wire is greater than in the thicker wires. (D) The current is the same in all the wires but the speed of the electrons in the thinner wire is less than in the thicker wire.
CURRENT ELECTRICITY (UNIT-7) MDCAT www.youtube.com/physicswithshahid Q7. A filament lamp has a resistance of 180 Ω when the current in it is 500 mA. What is the power transformed in the lamp? (A) 45W (B) 50W (C) 90W (D) 1400W Q8. Two cells X and Y are connected in series with a resistor of resistance 9.0Ω, as shown. Cell X has an electromotive force (e.m.f.) of 1.0V and an internal resistance of 1.0Ω. Cell Y has an e.m.f. of 2.0V and an internal resistance of 2.0 Ω. What is the current in the circuit? (A) 0.25 A (B) 0.17A (C) 0.10A (D) 0.083 A Q9. The graphs show the variation with potential difference V of the current/for three circuit elements. The three circuit elements are a metal wire at constant temperature, a semiconductor diode and a filament lamp. Which row of the table correctly identifies these graphs?
CURRENT ELECTRICITY (UNIT-7) MDCAT www.youtube.com/physicswithshahid Q10. Which graph best represents the variation with current I of potential difference V for a filament lamp? (A) (B) (C) (D) Q11. Two copper wires X and Y have the same volume. Wire Y is four times as long as wire X. What is the ratio resistance of wire Y resistance of wire X ? (A) 4 (B) 8 (C) 16 (D) 64 Q12. Two electrically-conducting cylinders X and Y are made from the same material. Their dimensions are as shown. What is the ratio resistance of X resistance of Y ? (A) 2 1 (B) 1 1 (C) 1 2 (D) 1 4 Q13. An iron wire has length 8.0 m and diameter 0.50 mm. The wire has resistance R. A second iron wire has length 2.0m and diameter 1.0 mm. What is the resistance of the second wire? (A) R 16 (B) R 8 (C) R 2 (D) R
CURRENT ELECTRICITY (UNIT-7) MDCAT www.youtube.com/physicswithshahid Q14. Four wires are made of the same metal. The cross-sectional areas, lengths and thermodynamic temperatures of the wires are shown. Which wire has the largest resistance? cross-sectional area length temperature A A 2L 2T B A L T C 2A 2L 2T D 2A L T Q15. The e.m.f. of the battery is 9.0V. The reading on the high-resistance voltmeter is 7.5V. What is the current I? (A) 0.10 A (B) 0.50 A (C) 0.60 A (D) 2.0 A Q16. What is meant by the electromotive force (e.m.f.) of a cell? (A) The e.m.f. of a cell is the energy converted into electrical energy when unit charge passes through the cell. (B) The e.m.f. of a cell is the energy transferred by the cell in driving unit charge through the external resistance (C) The e.m.f. of a cell is the energy transferred by the cell in driving unit charge through the internal resistance of the cell. (D) The e.m.f. of a cell is the amount of energy needed to bring a unit positive charge from infinity to its positive pole. Q17. A battery of negligible internal resistance is connected to two 10Ω resistors in series. What charge flows through each of the 10Ω resistors in 1 minute? (A) 0.30 C (B) 0.60C (C) 3.0C (D) 18C Q18. the terminal potential difference of a cell is greater than its emf when it is (A) being charged (B) being discharged (C) open circuit (D) either charged or discharged