Advertisements
Advertisements
Question
In which of the following cases more electrical energy is consumed per hour?
(i) A current of 1 ampere passed through a resistance of 300 ohms.
(ii) A current of 2 amperes passed through a resistance of 100 ohms.
Advertisements
Solution
(i) I = 1 A
R = 300 Î
t = 1 h
Electrical energy consumed = `I^2xxRxxt`
= (1)2 (300) (1)
= 300 Wh
(ii) I = 2 A
R = 100 Î
Electrical energy consumed = `I^2xxRxxt=(2)^2(100)(1)=400Wh`
Thus, more electrical energy is consumed in case (ii).
APPEARS IN
RELATED QUESTIONS
A student made an electric circuit shown here to measure the current through two lamps.
Are the lamps in series or parallel?
(a) Are the lamps in series or parallel?
(b) The student has made a mistake in this circuit. What is the mistake?
(c) Draw a circuit diagram to show the correct way to connect the circuit. Use the proper circuit symbols in your diagram.
A p.d. of 6 V is applied to two resistors of 3 Ω and 6 Ω connected in parallel. Calculate:
(a) the combined resistance
(b) the current flowing in the main circuit
(c) the current flowing in the 3 Ω resistor.
A 5 V battery is connected to two 20 Ω resistors which are joined together in series.
(a) Draw a circuit diagram to represent this. Add an arrow to indicate the direction of conventional current flow in the circuit.
(b) What is the effective resistance of the two resistors?
(c) Calculate the current that flows from the battery?
(d) What is the p.d. across each resistor?
Give three reasons why different electrical appliances in a domestic circuit are connected in parallel.
Which effect of current is utilised in an electric light bulb?
An electric current flowing in a wire creates ______ around the wire.
A bulb marked 12 V, 24 W operates on a 12 volt car battery for 20 minutes. Calculate:
(i) The current flowing through it, and
(ii) The energy liberated.
Two resistors of 4 Ω and 6 Ω are connected in parallel. The combination is
connected across a 6 volt battery of negligible resistance. Calculate:
( i) The power supplied by the battery,
(ii) The power dissipated in each resistor.
Tick(✓) the correct choice in the following:
When the length of a conductor is doubled the resistance of the conductor
will
Define the following:
Semiconductors
Fig. shows a 3 pin plug with the cover removed. The electric cable
connected to the plug contains 3 wires with colour coded insulation namely brown, blue and green.
- Identify each of the colour coded wires by stating to which of the
terminals A, B or C in the diagram they should be connected. - Identify the terminal through which no current passes in normal
circumstances. - What is the purpose of the earthed wire connected to an electric
appliance like an electric heater? Describe how it works.
Explain with the help of a diagram how does 'short circuiting' occur in an electric kettle.
A battery of e.m.f. 15 V and internal resistance 2 Ω is connected to two resistors of resistances 4 ohm and 6 ohm joined (a) in series. Find in each case the electrical energy spent per minute in 6 Ω resistor.
