Electricity: Class 10 Science Q&A · Page 5
281 free answers on Electricity (Science) for Class 10 students, across CBSE, ICSE and State boards.
Question & Answer
Questions
- ScienceClass 10ICSE
The commercial unit of energy is: a) Watt b) Watt-hour c) Kilowatt-hour Kilo-joule
The correct option is c) Kilowatt-hour Kilowatt hour is the commercial unit of energy.
- ScienceClass 10ICSE
The SI unit of energy is: a) Joule b) Coulomb c) Watt Ohm-meter
The correct answer is a) Joule The SI unit of energy is joule.
- ScienceClass 10ICSE
An electric heater is rated at 2kW. Electrical energy costs rupees 4 per kWh. What is the cost of using the heater for 3 hours? a) Rupees 12 b) Rupees 24 c) Rupees 36 Rupees 48
The correct option is b) Rupees 24. It is given that the electrical energy cost is Rupees 4/kWh Time duration is 3 hours The power of the electric heater is 2kW Using the given information we can calculate the amount for 3 hours as Rupees 24.
- ScienceClass 10ICSE
Which of the following is likely to be the correct wattage for an electric iron used in our homes? a) 60W b) 250 W c) 850W d) 2000W
The correct option is c) 850W The electric iron that is used in our homes have 850W power.
- ScienceClass 10ICSE
The unit for expressing electric power is: a) Volt b) Joule c) Coulomb Watt
The correct option is d) Watt Watt is the unit that is used for expressing the electric power.
- ScienceClass 10ICSE
When an electric lamp is connected to 12V battery, it draws a current of 0.5A. The power of the lamp is: a) 0.5W b) 6W c) 12W 24W
The correct option is b) 6W We know that power is calculated as P = VI. Substituting the values of V and I we get P = 6W.
- ScienceClass 10ICSE
An electric fan runs from the 230V mains. The current flowing through it is 0.4A. At what rate is electrical energy transferred by the fan?
Given, V = 230V I = 0.4ampRate at which electrical energy is transferred = Power P = VI P = 92watt = 92J/s
- ScienceClass 10ICSE
What is the maximum power in kilowatts of the appliance that can be connected safely to a 13A, 230V mains socket?
Given, I = 13amp V = 230V P = VI P = 2.99kW
- ScienceClass 10ICSE
A 2kW heater, a 200 watt TV and three 100 watt lamps are all switched on from 6-10PM. What is the total cost at Rupees 5.50 per kWh?
For heater, P = 2kWh T = 4 hours Energy consumed = PT = 8kWh For TV, P = 200 watt = 0.2kW T = 4 hours Energy consumed = PT = 0.8kWh For lamps, P = 100 watt = 0.1kW T = 4 hours n = 3 Energy consumed = PTn = 1.2kWh Total energy consumed = 8 + 0.8 + 1.2 = 10kWh Cost of 1kWh = Rupees 5.50 Total cost = Rupees 55.
- ScienceClass 10ICSE
An electric kettle connected to the 230V mains supply draws a current of 10A. Calculate: a) the power of the kettle the energy transferred in 1 minute
Given, V = 230V I = 10amp a) P = VI P = 2300 watt = 2300 J/s Energy consumed in one minute = PT = 138000 J
- ScienceClass 10ICSE
Calculate the power used in the 2Ω resistor in each of the following circuits: a) a 6V battery in series with 1Ω and 2Ω resistors a 4V battery in parallel with 12Ω and 2Ω resistors
Given, V = 6V R1 = 1 ohm R2 = 2 ohm Equivalent resistance, R = R1 + R2 = 3 ohm Total current, I = V/R = 6/3 = 2amp Current through R2 = I2 = I = 2amp Voltage across R2 = V2 = I2R2 = 4 ohm Power used in R2 = I2V2 = 8W b) V = 4V R1 = 12 ohm R2 = 2 ohm Voltage across R2 = V2 = V = 4V Current across R2 = I2 = V2/R2 = 2 amp Power used in R2 = I2V2 = 8W
- ScienceClass 10ICSE
Which uses more energy: a 250W TV set in 1 hour or a 1200W toaster in 10 minutes?
Case 1: TV set P = 250W = 0.25kWh T = 1 hour Energy consumed, E = PT = 0.25kWh Case 2: Toaster P = 1200W = 1.2kW T = 10 min = 1/6 hour Energy consumed, E = PT = 0.2kWh Therefore, it can be concluded that TV uses more power.
- ScienceClass 10ICSE
An electric motor takes 5 ampere current from a 220 volt supply line. Calculate the power of the motor and electric energy consumed by it in 2.
Given, I = 5amp V = 220V T = 2 hours P = ? E = ? P = VI P = 1.1kW Energy consumed E = PT E = 2.2kWh
- ScienceClass 10ICSE
For a heater rated at 4kW and 220V, calculate: a) the current b) the resistance of the heater c) the energy consumed in 2 hours the cost if 1 kWh is priced at Rupees 60
Given, P = 4kW V = 220V a) I = ? P = VI I = 16amp b) R = ? P = I2R R = 15.25 ohm Energy consumed in two hours = PT E = 8kWh If 1kWh = Rupees 6 Total cost = Rupees 36.8
- ScienceClass 10ICSE
A bulb is rated as 250V, 0.4A. Find a) Power Resistance
Given, V = 250V I = 0.4 amp a) P = ? P = VI P = 100 watt b) R = ? P = I2R R = 625 ohm
- ScienceClass 10ICSE
In a house two 60W electric bulbs are lighted for 4 hours and three 100W bulbs for 5 hour everyday. Calculate the electric energy consumed in 30 days.
Power, P1 = 60W Number, n1 = 2 Time for use, T1 = 4 hours everyday Energy consumed, E1 = n1 × P1 × T1 E1 = 2 × 60 × 4 = 480watt-hour = 0.48kWh Therefore, energy consumed for 30 days = 30 × 0.48 = 14.4watt-hour Case 2 Power, P2 = 100W Number, n2 = 3 Time for use T2 = 5 hours everyday Energy consumed, E2 = n2 × P2 × T2 E2 = 3 × 100 × 5 = 1500 = 1.5kWh Therefore, energy consumed for 30 d
- ScienceClass 10ICSE
An electric kettle rated at 220V, 2.2kW works for 3 hours. Find the energy consumed and the current drawn.
Given, V = 220V P = 2.2kW = 2200 watt T = 3 hours We know that Energy consumed = PT = 6.6kWh We also know that, P = VI Therefore, I = 10 amp
- ScienceClass 10ICSE
In which of the following cases more electrical energy is consumed per hour? a) A current of 1 ampere passed through a resistance of 300 ohms A current of 2 amperes passed through a resistance of 100 ohms
Answer: Given, R = 300 ohm I = 1 amp T = 1 hour P = I2R = 300W E = PT = 300 watt-hour Given, R = 100 ohm I = 2 amp T = 1 hour P = I2R = 400W E = PT = 400 watt-hour Therefore, in second case the consumption of electrical energy per hour is more.
- ScienceClass 10ICSE
An electric bulb is connected to a 220V power supply line, if the bulb draws a current of 0.5A, calculate the power of the bulb.
Given, V = 220V I = 0.5A P = ? We know that, P = VI P = 110 watt
- ScienceClass 10ICSE
How much energy is consumed when a current of 5 ampere flows through the filament of a heater having resistance of 100 ohms for two hours? Express it in joules.
Given, I = 5A R = 100 ohm T = 2 hours We know that, Energy consumed = P × T = I2RT Substituting the values, Energy consumed = 5kWh 1kWh = 3.6 × 106J Therefore, 5kWh = 5 ×3.6 × 106J = 18 × 106J