Advertisements
Advertisements
प्रश्न
A resistor of resistance R is connected to an ideal battery. If the value of R is decreased, the power dissipated in the resistor will ______________ .
पर्याय
increase
decrease
remain unchanged
उत्तर
increase
As the resistance is connected to an ideal battery, it provides a constant potential difference across the two terminals. The internal resistance of the battery is also zero.
The power dissipated in the resistor,
P = \[\frac{V^2}{R}\]
V is constant; hence V \[\propto \frac{1}{R^{}}\]
Thus, if the value of the resistance is decreased, the power dissipated in the resistor will increase.
APPEARS IN
संबंधित प्रश्न
An electric kettle connected to the 230 V mains supply draws a current of 10 A. Calculate:
(a) the power of the kettle.
(b) the energy transferred in 1 minute.
The unit for expressing electric power is:
(a) volt
(b) joule
(c) coulomb
(d) watt
How many joules of electrical energy are transferred per second by a 6 V; 0.5 A lamp?
(a) 30 J/s
(b) 12 J/s
(c) 0.83 J/s
(d) 3 J/s
When a current of 4.0 A passes through a certain resistor for 10 minutes, 2.88 × 104 J of heat are produced. Calculate
the power of the resistor.
the voltage across the resistor.
Name the S.I. unit of electrical energy. How is it related to Wh?
1kWh = …….. J
A current of 2 A is passed through a coil of resistance 75Ω for 2 minutes. (a) How much heat energy is produced? (b) How much charge is passed through the resistance?
An electric bulb, when connected across a power supply of 220 V, consumes a power of 60 W. If the supply drops to 180 V, what will be the power consumed? If the supply is suddenly increased to 240 V, what will be the power consumed?
Fig . shows the essent ial features of a battery operated bell. The hammer strikes the gong when the swi tch is closed . State and explain the effect of using the following material successively to form the core.
(a) Plastic
(b) Steel
(c) Copper
How does earthing prevent electrical shock?
How is the amount of heat produced calculated due to the passage of current in a metallic conductor? Derive an expression for it.
State (i) the S. I. unit, (ii) the household unit, of electrical energy. How are these units related?
An electric bulb is rated as 100W – 250V. What information does it convey? Calculate the current through the filament of the bulb.
Two bulbs are rated: bulb A 100W, 120 V bulb B 10 W, 120 V. If both are connected across a 120V supply, which bulb will consume more energy, When in parallel? Also calculate the current through each bulb in the above cases.
A. bulb is rated at 100W, 250V and another one at 60W, 250V. What is the current flowing in the circuit if the two bulbs are put in series across a 220 V mains supply?
A torch bulb is rated at 3 V and 600 mA. Calculate it’s
- power
- resistance
- energy consumed if it is used for 4 hours.
1 kWh is equal to:
Electric power is inversely proportional to ____________.
A student wants to use an electric heater, an electric bulb and an electric fan simultaneously.
How should these gadgets be connected with the mains? Justify your answer giving three reasons.