281. In a conductor, if 1500 coulombs of charge enter and 1500 coulombs of charge exit in 5 minutes, what is the electric current?
Answer: 5 Amperes
282. Two wires made of the same material have a length and radius ratio of 3:4 and 3:2 respectively, and are connected in parallel to a 6V battery. What is the ratio of the electric currents?
Answer: 3:1
283. How many resistors of 400 Ω are required to carry a current of 5 Amperes connected to a 200 V line?
Answer: 10
284. Indicate which of the following arrangements can be used to verify Ohm’s law?
Answer: (Image A)
285. The V-I graph for the series and parallel combinations of the two given resistors R₁ and R₂ is shown below. Which graph is correctly labeled?
Answer: Both figure (i) and figure (ii)
286. In the given circuit diagram, what is the number indicated by the voltmeter?
Answer: 5 V
287. A wire with a resistance of 8 ohms has been bent to form a closed circle. What is the effective resistance between points A and B?
Answer: 3/2 Ω
288. An electric heater is rated at 1 kW. Calculate the heat produced per hour.
Answer: 3600 x 10³ J
289. The S.I. unit of resistivity is
Answer: Ohm meter
290. Heaters A and B are rated at 200W and 40W respectively at 220V and are connected in parallel to a 220V supply. Calculate the current drawn by heater B.
Answer: 0.182 A
291. A small electric generator in your house produces 45 kJ of energy. How long can you run a 45W incandescent bulb with it?
Answer: 16.67 minutes
292. A student receives the following graph: (The graph has current (I) in mA and voltage (V) in volts). What is the resistance of the resistor?
Answer: 2 kΩ
293. Which of the following statements about the properties of magnetic field lines is not true?
Answer: These force lines are very close together in a magnetic field.
294. In an experiment, a current-carrying conductor is placed parallel to the magnetic needle of a compass. If the direction of the current is from south to north, then:
Answer: The north pole of the needle turns towards the west.
295. The strength of the magnetic field around a long straight current-carrying wire:
Answer: Is inversely proportional to the distance from the wire.
296. The direction of the force on a current-carrying wire placed in a magnetic field depends on:
Answer: Both the direction of the current and the direction of the field
297. An electric fuse is based on:
Answer: The thermal effect of electric current
298. The purpose of the glass cover on the top of a box-type solar cooker is:
Answer: To reduce heat loss by radiation
299. To operate efficiently, a wind turbine typically requires a minimum wind speed of about ……..
Answer: 15 km/h
300. Which of the following energy types is derived from the sun?
Answer: Solar energy