Tiêu đề 18. Current Electricity.pdf ✅

1. In the circuit shown in the adjoining figure, the reading of ammeter A is:- (1) 1 A (2) 2 A (3) 3 A (4) 4 A 2. In the adjoining figure the emf of the cell is 2V and internal resistance is negligible. The resistance of the voltmeter is 80 ohm. The reading of voltmeter will be :- (1) 2.00 volt (2) 1.33 volt (3) 1.60 volt (4) 0.80 volt 3. In the adjoining circuit, the galvanometer G shows zero deflection. If the batteries A and B have negligible internal resistance, the value of the resistor R will be :- (1) 500  (2) 1000  (3) 200  (4) 100  4. In a metre bridge experiment, resistances are connected as shown in the following figure. The balancing length is 1 55 cm. Now, an unknown resistance x is connected in series with P and the new balancing length is found to be 75 cm. The value of x is :- 5. An electric kettle (rated accurately at 2.5 kW) is used to heat 3 kg of water from 15°C to boiling point. It takes 9.5 minute. Then, the amount of heat that has been lost is :- (1) 3.5 × 105 J (2) 7 × 106 J (3) 3.5 × 104 J (4) 7 × 108 J 6. In the figure shown, if the internal resistance of the battery is 1 ohm, the reading of the ammeter will be : (1) 1 A (2) 2 A (3) 3 A (4) 4 A 7. In the circuit shown, the reading of the Ammeter is doubled after the switch is closed. Each resistor has a resistance = 1  and the ideal cell has an e. m.f. = 10 V. Then, the Ammeter has a coil resistance equal to (1) 2  (2) 1  (3) 2.5  (4) None 8. With a potentiometer null point were obtained at 140 cm and 180 cm for cells of emf 1.1 V and one unknown X volt. Unknown emf is:- (1)1.1 V (2) 1.8 V (3) 2.4 V (4) 1.41 V 9. A battery of 10 cells each of e.m.f. E = 1.5 V and internal resistance 0.5 has 1 cell wrongly connected. It is being charged by Current Electricity

potential difference between the points C and D, where should jockey be pressed (1) 32 cm (2) 16 cm (3) 8 cm (4) 4 cm 19. To get maximum current in a resistance of 3 one can use n rows of m cells connected in parallel. If the total no. of cells is 24 and the internal resistance of a cell is 0.5 then (1) m = 12, n = 2 (2) m = 8, n = 4 (3) m = 2, n = 12 (4) m = 6, n = 4 20. Consider the circuit shown in the figure. The current i3 is equal to (1) 5 amp (2) 3 amp (3) – 3 amp (4) – 5/6 amp 21. Water boils in an electric kettle in 15 minutes after switching on. If the length of the heating wire is decreased to 2/3 of its initial value, then the same amount of water will boil with the same supply voltage in (1) 15 minutes (2) 12 minutes (3) 10 minutes (4) 8 minutes 22. A capacitor of 4F is connected as shown in the circuit. The internal resistance of the battery is 0.5.The amount of charge on the capacitor plates will be:- (1) 0 (2) 4C (3) 16C (4) 8C 23. A wire has a non-uniform cross-sectional area as shown in figure. A steady current i flows through it. Which one of the following statement is correct (1) The drift speed of electron is constant (2) The drift speed increases on moving from A to B (3) The drift speed decreases on moving from A to B (4) The drift speed varies randomly 24. Two resistances R1 and R2 provides series to parallel equivalents as 1 n then the correct relationship is 25. Two wires of equal diameters of resistivity 1, 2and length x1, x2 respectively are joined in series. The equivalent resistivity is – 26. The V-i graph for a conductor at temperature T1and T2 are as shown in the figure. (T2 – T1) is proportional to :- (1) cos 2 (2) sin
(3) cot 2 (4) tan 27. A uniform wire connected across a supply produces heat H per second. If the wire is cut in ton equal parts and all the parts are connected in parallel across the same supply, the heat produced per second will be 28. The figure shows a part of a circuit. Find potential of point P. 29. Find the equivalent resistance between P and Q. (If each wire has a resistance R) :- 30. The graph between resistance (R) and mass (m) of a wire of given material if its radius remains constant is– (1) 2 (2) 3 \ (3) 4 (4) 1 31. A potentiometer wire of length 1m has a resistance 20. It is connected in series with a resistance R and a cell of emf 2 volts. If potential gradient is 1V/m. Find R (1) 2 (2) 18 (3) 20 (4) 40 32. In experiment of measurement of internal resistance of a cell the reading of ammeter is2A when load resistance (Re) is 3. If load resistance is 6  the reading of ammeter is1.25A. What will be reading of ammeter when load is 8? 33. A uniform wire of resistance 20 ohm having resistance 1/m is bent in the adjoining form of a circle as shown in the figure. If the equivalent resistance between M and N is 1.8 , then the length of the shorter section is:- (1) 2m (2) 5m (3) 1.8 m (4) 18 m 34. In the network shown in the adjoining figure, each resistance is 1 ohm. The effective resistance between A and B is:- (1) (4/3) (2) (3/2) (3) 7 (4) (8/7)  35. Two resistances of 400 and 800 are connected in series with a 6 volt battery of negligible internal resistance. A voltmeter of resistance 10,000  is used to measure the potential difference across400 . The error in the measurement of potential difference (in volt) approximately is:- (1) 0.01 (2) 0.02 (3) 0.04 (4) 0.05 36. To get maximum current through a resistance of 2.5 , one can use m rows of cells, each row having n cells. The internal resistance of each cell is 0.5 . What are the values of n and m if the total number of cells is 45? (1) m= 3, n = 15 (2) m = 5, n = 9 (3) m = 9, n = 5 (4) m = 15, n = 3 37. In an electrolyte 3.2 × 1018 bivalent positive ions drift to the right per second while 3.6 × 1018monovalent negative ions drift to the left per second. The, the current is:-