Energy And Power MCQs with Explanations

To calculate power (P), you can use the formula: P = Energy (E) / Time (t) In this case, the energy is 12,000 J , and the time is 400 ms , which needs to be converted to seconds: 400 ms = 0.4 seconds Now, you can calculate the power: P = 12,000 J / 0.4 s = 30,000 W = 30 kW So, the correct answer is Option A: 30 kW , as the power is 30,000 watts or 30 kilowatts, which represents the rate at which energy is used or transferred.

We need to find the power rating of the resistor. The formula we'll use is: P = I 2 R , where: * P is the power (in Watts) * I is the current (in Amperes) * R is the resistance (in Ohms) First, convert the current from milliamperes (mA) to amperes (A): 25 mA = 25 / 1000 A = 0.025 A Now, plug the values into the formula: P = (0.025 A) 2 * 120 Ω P = 0.000625 * 120 W P = 0.075 W Convert Watts(W) to milliWatts(mW): 0. 075 W = 0.075 * 1000 mW = 75 mW So, the resistor rating should be at least 75 mW .

To determine which resistor will overheat, we need to calculate the power dissipated in each resistor and compare it with their power rating (0.5 watts). Using the power formula: P = V² / R For the 33 Ω resistor: P = (12)² / 33 = 144 / 33 ≈ 4.36 watts This is much greater than 0.5 watts, so the 33 Ω resistor will overheat. For the 330 Ω resistor: P = (12)² / 330 = 144 / 330 ≈ 0.436 watts This is less than 0.5 watts, so the 330 Ω resistor will NOT overheat. Conclusion: Only the 33 Ω resistor will overheat.

25.7 V is the correct answer to “A 220 Ω resistor dissipates 3 W. The voltage is”. This question is standard in competitive examination syllabi for Energy And Power.

12 kWh is the correct answer to “If you used 400 W of power for 30 h, you have used”. This question is standard in competitive examination syllabi for Energy And Power.

All of the above is the correct answer to “For 12 V and 40 mA, the power is”. This question is standard in competitive examination syllabi for Energy And Power.

1,170 Wh is the correct answer to “How many watt-hours represent 65 W used for 18 h”. This question is standard in competitive examination syllabi for Energy And Power.

True is the correct answer to “Energy equals power multiplied by time.”. This question is standard in competitive examination syllabi for Energy And Power.

False is the correct answer to “Watt's law states the relationships of power to energy.”. This question is standard in competitive examination syllabi for Energy And Power.

8.7 mA is the correct answer to “A 3.3 kΩ resistor dissipates 0.25 W. The current is”. This question is standard in competitive examination syllabi for Energy And Power.

85.7 % is the correct answer to “A power supply produces a 0.6 W output with an input of 0.7 W. Its percentage of efficiency is”. This question is standard in competitive examination syllabi for Energy And Power.

4.28 A is the correct answer to “How much continuous current can be drawn from a 60 Ah battery for 14 h”. This question is standard in competitive examination syllabi for Energy And Power.

1.286 kWh is the correct answer to “At the end of a 14 day period, your utility bill shows that you have used 18 kWh. What is your average daily power”. This question is standard in competitive examination syllabi for Energy And Power.

2,000 h is the correct answer to “A 6 V battery is connected to a 300 Ω load. Under these conditions, it is rated at 40 Ah. How long can it supply current to the load”. This question is standard in competitive examination syllabi for Energy And Power.

False is the correct answer to “The capacity of a battery is measured in milli-amperes.”. This question is standard in competitive examination syllabi for Energy And Power.

0.938 Wh is the correct answer to “A 15 V source is connected across a 12 Ω resistor. How much energy is used in three minutes”. This question is standard in competitive examination syllabi for Energy And Power.

500 mW is the correct answer to “A half-watt is equal to how many milliwatts”. This question is standard in competitive examination syllabi for Energy And Power.

40,000 W is the correct answer to “In 40 kW, there are”. This question is standard in competitive examination syllabi for Energy And Power.

True is the correct answer to “The joule is a unit of energy.”. This question is standard in competitive examination syllabi for Energy And Power.

False is the correct answer to “Energy is equal to power multiplied by voltage.”. This question is standard in competitive examination syllabi for Energy And Power.

21 Ah is the correct answer to “A given power supply is capable of providing 6 A for 3.5 h. Its ampere-hour rating is”. This question is standard in competitive examination syllabi for Energy And Power.

25 mW is the correct answer to “In 0.025 W, there are”. This question is standard in competitive examination syllabi for Energy And Power.

20 W is the correct answer to “Three hundred joules of energy are consumed in 15 s. The power is”. This question is standard in competitive examination syllabi for Energy And Power.

132 mW is the correct answer to “A 68 Ω resistor is connected across the terminals of a 3 V battery. The power dissipation of the resistor is”. This question is standard in competitive examination syllabi for Energy And Power.

True is the correct answer to “A battery is one type of power supply that converts chemical energy into electrical energy.”. This question is standard in competitive examination syllabi for Energy And Power.

Shorted is the correct answer to “When the pointer of an analog ohmmeter reads close to zero, the resistor being measured is”. This question is standard in competitive examination syllabi for Energy And Power.

2 W is the correct answer to “The power rating of a carbon-composition resistor that is to handle up to 1.2 W should be”. This question is standard in competitive examination syllabi for Energy And Power.

12 V is the correct answer to “A 75 Ω load uses 2 W of power. The output voltage of the power supply is approximately”. This question is standard in competitive examination syllabi for Energy And Power.

201.6 kWh is the correct answer to “A certain appliance uses 350 W. If it is allowed to run continuously for 24 days, how many kilowatt-hours of energy does it consume”. This question is standard in competitive examination syllabi for Energy And Power.

768 mW is the correct answer to “When the current through a 12 kΩ resistor is 8 mA, the power is”. This question is standard in competitive examination syllabi for Energy And Power.

True is the correct answer to “The watt is the unit of power.”. This question is standard in competitive examination syllabi for Energy And Power.

True is the correct answer to “A resistor normally opens when it burns out.”. This question is standard in competitive examination syllabi for Energy And Power.

False is the correct answer to “The power rating of a resistor determines the minimum power that it can handle safely.”. This question is standard in competitive examination syllabi for Energy And Power.

False is the correct answer to “Power rating is related to resistance value.”. This question is standard in competitive examination syllabi for Energy And Power.