- Draw a schematic diagram of a circuit consisting of a battery of three cells of 2 V each, a 5
$\Omega$ resistor, an 8 $\Omega$ resistor, and a 12 $\Omega$ resistor, and a plug key, all connected
in series.
- In the circuit of Q1, redraw it putting an ammeter to measure the current through the resistors and
a voltmeter to measure the potential difference across the 12 $\Omega$ resistor.
- How would you connect three resistors, each of resistance 6 $\Omega$, so that the combination has a
resistance of (i) 9 $\Omega$, (ii) 4 $\Omega$?
- Three resistors of 2 $\Omega$, 3 $\Omega$ and 6 $\Omega$ are connected in parallel. Draw the circuit
diagram.
- A wire of resistance R is bent in the form of a closed circle. What is the effective resistance
between the two ends of any diameter?
- You are given n resistors each of resistance R. How will you combine them to get the (i) maximum and
(ii) minimum effective resistance? What is the ratio of the maximum to minimum resistance?
- Study the following circuit: Two resistors 3 $\Omega$ and 6 $\Omega$ connected in parallel, and this
combination is connected in series with a 4 $\Omega$ resistor and a 12V battery. Calculate total
resistance.
- In the circuit mentioned in Q7, what is the current flowing through the 12V battery?
- For the same circuit (Q7), find the potential drop across the 4 $\Omega$ resistor.
- Find the current passing through the 6 $\Omega$ resistor in the circuit described in Q7.
- Draw a circuit diagram to show how two resistors are connected in series with a battery and an
ammeter. Where should the voltmeter be placed to measure voltage across one resistor?
- In a series circuit, if one bulb fuses, why do the others go off? Explain with a diagrammatic
concept.
- Why is the parallel arrangement used in domestic wiring? Explain using the concept of voltage
stability.
- Two lamps, one rated 100 W at 220 V, and the other 60 W at 220 V, are connected in parallel. Draw
the circuit.
- What is the function of an electric fuse? Where is it placed in the circuit? Draw a symbol for a
fuse.
- A potential difference of 250 V is applied across a resistance of 500 $\Omega$. Calculate the
current passing through it.
- A resistance of 20 $\Omega$ has a current of 2 A flowing through it. What is the potential
difference across it?
- Calculate the resistance of a conductor if the current flowing through it is 0.2 A when the applied
potential difference is 0.8 V.
- A copper wire of length 2 m and area of cross-section $1.7 \times 10^{-6} m^2$ has a resistance of
$2 \times 10^{-2} \Omega$. Calculate the resistivity of copper.
- A piece of wire of resistance 20 $\Omega$ is drawn out so that its length is increased to twice its
original length. Calculate the resistance of the wire in the new shape.
- Two resistors, with resistances 5 $\Omega$ and 10 $\Omega$ respectively are to be connected to a
battery of emf 6 V so as to obtain: (i) minimum current (ii) maximum current. (a) How will you
connect the resistances in such case? (b) Calculate the strength of the total current in the circuit
in the two cases.
- A hot plate of an electric oven connected to a 220 V line has two resistance coils A and B, each of
24 $\Omega$ resistance. Calculate current when coils are used: (i) separately, (ii) in series, (iii)
in parallel.
- Compare the power used in the 2 $\Omega$ resistor in each of the following circuits: (i) a 6 V
battery in series with 1 $\Omega$ and 2 $\Omega$ resistors, and (ii) a 4 V battery in parallel with
12 $\Omega$ and 2 $\Omega$ resistors.
- Two lamps, one rated 100 W at 220 V, and the other 60 W at 220 V, are connected in parallel to
electric mains supply. What current is drawn from the line if the supply voltage is 220 V?
- Which uses more energy: a 250 W TV set in 1 hr, or a 1200 W toaster in 10 minutes?
- An electric heater of resistance 8 $\Omega$ draws 15 A from the service mains 2 hours. Calculate the
rate at which heat is developed in the heater.
- 100 J of heat is produced each second in a 4 $\Omega$ resistance. Find the potential difference
across the resistor.
- An electric bulb connects to a 220 V generator. The current is 0.50 A. What is the power of the
bulb?
- An electric refrigerator rated 400 W operates 8 hour/day. What is the cost of the energy to operate
it for 30 days at Rs 3.00 per kWh?
- Find the energy consumed by a bulb of 500 W in 4 hours. Express your answer in Joules.
- A torch bulb is rated 2.5 V and 750 mA. Calculate (i) its power, (ii) its resistance, (iii) the
energy consumed if this bulb is lighted for 4 hours.
- Calculate the heat produced when 96000 C of charge is transferred in 1 hour through a potential
difference of 50 V.
- A current of 4 A flows through a 12 V car headlight bulb for 10 minutes. How much energy transfer
occurs during this time?
- Calculate the current through a 60 W lamp rated for 250 V. If the line voltage falls to 200 V, how
is power consumed affected? (Assuming R remains constant).
- Two bulbs A and B are rated 100W - 120V and 10W - 120V respectively. They are connected across a
120V source in series. Which bulb will consume more power?
- Why is tungsten used for the filament of reaction lamps? Give two reasons.
- Why are the conductors of electric heating devices, such as bread-toasters and electric irons, made
of an alloy rather than a pure metal?
- Why is the series arrangement not used for domestic circuits?
- How does the resistance of a wire vary with its cross-sectional area? Explain on the basis of
electron collisions.
- Why do electricians wear rubber gloves while working?
- Why is copper/aluminum used for transmission lines?
- Explain why the resistance of a conductor increases with increase in temperature.
- Why should a fuse wire have a low melting point?
- Why should an ammeter have very low resistance?
- Why should a voltmeter have very high resistance?
- What is the role of the earth wire in domestic circuits?
- Does the resistivity of an alloy change with temperature? How is it different from pure metals?
- Why is parallel connection preferred for connecting bulbs in a house?
- Explain the term 'Overloading' in an electric circuit.
- Explain the term 'Short Circuiting'. How does a fuse protect against it?
