Advertisements
Advertisements
प्रश्न
What is the resistance of an appliance rated at V volt, P watt?
Advertisements
उत्तर
Let I be the current drawn by the appliance.
Then Power, P = V × I or I = `"P"/"V"`
Now, Resistance R = `"V"/"I"`
Hence, R = V + `"P"/"V" = "V"^2/"P"`.
संबंधित प्रश्न
What determines the rate at which energy is delivered by a current?
A 2 kWh heater, a 200 W TV and three 100 W lamps are all switched on from 6 p.m. to 10 p.m. What is the total cost at Rs 5.50 per kWh?
Two bulbs are rated 60 W, 220 V and 60 W, 110 V respectively. Calculate the ratio of their
resistances
Express watt hour and kilowatt hour in joule.
What do you understand by ‘earthing’? What are the advantages of earthing in a household electric circuit? Explain, how it is done?
How does earthing prevent electrical shock?
The equation I2R seems to suggest that the rate of heating in a resistor is reduced if resistance decreases, whereas equation P = V2/R suggests just the opposite. How do you reconcile this problem?
A bulb is marked 100W, 220V and an electric heater is marked 2000 W, 220 V.
(i) What is the ratio between the resistances of these two devices?
(ii) How does the power-voltage rating of a device help us to decide about the type of leads (connecting wires) to be used for it?
(iii) In which of the above two devices, a thicker connecting wire of lead is required?
Electric power is inversely proportional to ____________.
