Basic Electricity
Workshop Calculation and Science, Module-7
Q1: Which machine converts mechanical energy into electrical energy?
- Battery
- Generator
- Heater
- Iron box
Q2: Which is the unit of current?
- Ampere
- Volt
- Ohm
- Watt
Q3: Which is the unit of resistance?
- Ampere
- Volt
- Ohm
- Watt
Q4: What is the flow of electrons in any conductor?
- Voltage
- Current
- Resistance
- Power
Q5: Which property of a substance is opposing the flow of electric current?
- Current
- Voltage
- Resistance
- EMF
Q6: Which is very good conductor?
- Copper
- Cast iron
- Wrought iron
- Steel
Q7: Which is mineral insulator?
- Glass
- Quartz
- Mica
- Porcelain
Q8: What is the total resistance if three resistances of 3 ohms, 9 ohms and 5 ohms are connected in series?
- 11 ohms
- 7 ohm
- 17 ohms
- 1/17 ohms
Show Explanation
In series: \[ R_{\text{total}} = R_1 + R_2 + R_3 = 3 + 9 + 5 = 17\ \Omega \]
Q9: What is the total resistance if two resistances of 4 ohms and 6 ohms are connected in parallel?
- 12.4
- 24
- 2.4
- 10
Show Explanation
In parallel: \[ \frac{1}{R} = \frac{1}{4} + \frac{1}{6} = \frac{5}{12} \Rightarrow R = \frac{12}{5} = 2.4\ \Omega \]
Q10: What is the total resistance if three resistances of 4 ohms, 6 ohms and 8 ohms respectively are connected in parallel?
- 24
- \(\frac{24}{13}\)
- \(\frac{13}{24}\)
- 13
Show Explanation
\[ \frac{1}{R} = \frac{1}{4} + \frac{1}{6} + \frac{1}{8} = \frac{13}{24} \Rightarrow R = \frac{24}{13} \Omega \]
Q11: Which is same in series connection of resistors in a circuit?
- Current
- Voltage
- Resistance
- Power
Q12: Which law states that at constant temperature the current passing through a closed circuit is directly proportional to the potential difference and inversely proportional to the resistance?
- Ohm's law
- Lenz's law
- Newton's law
- Hooke's law
Q13: What is the resistance? I = 11.5 Amps, V = 380 Volts, R = _______Ohms
- 13 ohms
- 23 ohms
- 33 ohms
- 43 ohms
Show Explanation
\[ R = \frac{V}{I} = \frac{380}{11.5} \approx 33.04\ \Omega \]
Q14: What is the current? R = 50 Ohms, 220 Volts, I =______Amps
- 4.1 Amps
- 4.2 Amps
- 4.3 Amps
- 4.4 Amps
Show Explanation
\[ I = \frac{V}{R} = \frac{220}{50} = 4.4\ \text{Amps} \]
Q15: What is the voltage? R = 250 Ohms, I = 0.44 Amps, V = _____Volts
- 100 Volts
- 105 Volts
- 108 Volts
- 110 Volts
Show Explanation
\[ V = I × R = 0.44 × 250 = 110\ \text{Volts} \]
Q16: Which statement is correct according to ohm's law?
- I ∝ 1/V
- I ∝ R
- I ∝ V/R
- I ∝ R/V
Q17: What is the filament resistance if a 6 volt bulb draws a current of 0.5 Amps?
- 12 W
- 10 W
- 3 W
- 1.2 W
Show Explanation
\[ R = \frac{V}{I} = \frac{6}{0.5} = 12\ \Omega \]
Q18: How much watt second in 1 watt hour?
- 1000 watt sec
- 2000 watt sec
- 3600 watt sec
- 4000 watt sec
Show Explanation
\[ 1\ \text{Watt-hour} = 1\ \text{W} \times 3600\ \text{seconds} \]\[= 3600\ \text{Ws} \]
Q19: What is the power if an emf of one volt causes a current flow of 1 ampere?
- 1 watt
- 1 kilowatt
- 1 HP
- 1 Kilowatt hour
Show Explanation
\[ P = V × I = 1 × 1 = 1\ \text{watt} \]
Q20: Which is equal to electric power?
- R²I watts
- I²R watts
- \(\frac{R²}{I}\) watts
- \(\frac{I²}{R}\) watts
Q21: How much power does it consumes if an electric heater draws a current of 10 amps at 200 volts?
- 2000 watts
- 2010 watts
- 2020 watts
- 2030 watts
Show Explanation
\[ P = V × I = 200 × 10 = 2000\ \text{watts} \]
Q22: What is the resistance of an electric iron if the rating of electric iron is 220 V and 500 watts?
- 94.8 ohms
- 95.8 ohms
- 96.8 ohms
- 97.8 ohms
Show Explanation
\[ R = \frac{V^2}{P} = \frac{220^2}{500} = 96.8\ \Omega \]
Q23: What is the voltage of the immersion heater? P = 500 watts, I = 2.27 Amps, V = ______Volts
- 200.3 volts
- 210.3 volts
- 220.3 volts
- 230.3 volts
Show Explanation
\[ V = \frac{P}{I} = \frac{500}{2.27} \approx 220.3\ \text{Volts} \]
Q24: What is the unit of intensity of magnetic field?
- wb/m
- m/wb
- Hertz
- Coloumb
Q25: Which law states about electromagnetic induction?
- Ohm's law
- Hooke's law
- Lenz's law
- Faraday's law
Q26: What is the formual for induced emf?
- B²L sinθ volts
- BL sinθ volts
- BLV sinθ volts
- B²V sinθ volts
Q27: What does EMF stands for?
- Electronic Magnetic Force
- Electro Motive Force
- Electro Magnetic Force
- Electromated Force
Q28: Which is the example for statically induced emf?
- Generator
- Motor
- Transformer
- Refrigerator
Q29: Which is the example for dynamicallly induced Emf?
- Motor
- Generator
- Car
- Motor bike
Q30: Which is the unit electrical power?
- Volts
- Ohms
- Watts
- Ampere
Q31: What is the current Flow in the bulb? P = 550 watts, R = 22 Ohms, I = ______Amps
- 2 Amps
- 3 Amps
- 4 Amps
- 5 Amps
Show Explanation
\[ I = \sqrt{\frac{P}{R}} = \sqrt{\frac{550}{22}} = \sqrt{25} = 5\ \text{Amps} \]
Q32: What is the power required? I = 0.455 Amps, R = 484 Ohms, P = _____Watts
- 98.2 watts
- 99.2 watts
- 100.2 watts
- 101.2 watts
Show Explanation
\[ P = I^2 \ × R = (0.455)^2 × 484 \approx 0.207 × 484 \]\[\approx 100.2\ \text{watts} \]
Q33: What is the rated power if an adjustable resistor bears the following label 1.5 k ohms/0.08A?
- 9.2 watts
- 9.4 watts
- 9.6 watts
- 9.8 watts
Show Explanation
\[ P = I^2 × R = (0.08)^2 × 1500 \]\[= 0.0064 × 1500 = 9.6\ \text{watts} \]
Q34: How much voltage will be required to illuminate a 40 watts fluorescent lamp draws a current of 0.10 amperes?
- 390 volts
- 395 volts
- 400 volts
- 405 volts
Show Explanation
\[ V = \frac{P}{I} = \frac{40}{0.10} = 400\ \text{Volts} \]
Q35: How many hours will take for a 100 watts bulb to consume 1 kwh energy?
- 10 hours
- 12 hours
- 18 hours
- 24 hours
Show Explanation
\[ t = \frac{1\ \text{kWh}}{100\ \text{W}} = \frac{1000\ \text{Wh}}{100\ \text{W}} = 10\ \text{hours} \]