Physics toasters etc.

Grade 10 Reason (R): Alloys do not oxidise (burn) readily at high temperatures.
Revision Question Bank 5. Assertion (A): When the resistances are connected end-to-end
1. In an electrical circuit two resistors of 2 Ω and 4 Ω respectively are consecutively, they are said to
connected in series to a 6V battery. The heat dissipated by the 4 Ω be in series.
resistor in a 5s will be Reason (R): In case the total resistance is to be increased, then the
(a) J (b) 10J (c) 20J (d) 30J individual resistances are
2. An electric kettle consumes 1KW of electric power when operated at connected in series.
220V. A fuse wire of what rating must be used for it? 1. In the following circuit diagram, calculate the resistance offered by
(a) 1A (b) 2A (c) 4A (d) 5A the combination if the current enters at A and leaves at D.
3. Two resistors of resistance 2 Ω and 4 Ω when connected to a battery
will have
(a) Same current flowing through them when connected in parallel
(b) Same current flowing through them when connected in series
(c) Same potential difference across them when connected in series
(d) Different potential difference across them when onnected in 2. (a) Define power and state its SI unit.
parallel (b) A torch bulb is rated 5V and 500mA. Calculate its
4. Unit of electric power may also be expressed as (i) Power
(a) Volt ampere (c) kilowatt hour (ii) Resistance
(b) Watt second (d) joule second (iii) Energy consumed when it is lighted for 21/2 hours.
5. The resistivity does not change if 3. An electric lamp of resistance 20 ohm and a conductor of resistance
(a) The material is changed 4ohm are connected to a 6V battery as shown in the circuit. Calculate:
(b) The temperature is changed
(c) The shape of the resistor is changed
(d) Both material and temperature are changed
1. Assertion (A): Tungsten metal is used for making filaments of
incandescent lamps.
Reason (R): The melting point of tungsten is very low. (i) The total resistance of the circuit,
2. Assertion (A): If a graph is plotted between the potential difference (ii) The current through the circuit,
and the current flowing, (iii) The potential difference across the (i) electric lamp and (ii)
the graph is a straight line passing through the origin. conductor, and
Reason (R): The current is directly proportional to the potential (iv) Power of the lamp
difference. 4. (a) List two disadvantages of using a series circuit in homes.
3. Assertion (A): Longer wires have greater resistance and the smaller (b) Calculate the effective resistance between A and B in the circuit
wires have lesser resistance. given below:
Reason (R): Resistance is inversely proportional to the length of the
wire.
4. Assertion (A): Alloys are commonly used in electrical heating
devices, like electrical iron,
 (a) The value of current through each resistor
(b) The total current in the circuit
(c) The total effective resistance of the circuit
23. State Ohm’s law? How can it be verified experimentally?
5. What is the difference between a conductor and an insulator? 24. If there are 3 x 1011 electrons flowing through the filament of the
6. What is the difference between open and closed circuits? Draw bulb for two minutes. Find the current flowing through the circuit.
diagrams for both. Charge on one electron 1.6 x 1019 C.
7. Define parallel connection and series connection. 25. Three resistors of 5 Ω, 10 Ω and 15 Ω are connected in series, and the
8. What are the disadvantages of heating effect of current?
entire combination is connected to a battery of 30 V. Ammeter and
9. What are the advantages of heating effect of current?
10. What is electric current? Voltmeter are connected in the circuit. Draw a circuit diagram to
11. What is potential difference? Give its unit with definition. connect all the devices in the proper, correct order. What is the
12. Find the expression for calculating heat. current flowing and potential difference across 10 Ω resistance?
13. A wire is 1m long, 0.2mm in diameter and has resistance of 10Ω. 26. If an electric heater rated 800 W operates 6h/day. Find the Cost of
Calculate its resistivity. energy to operate it for 30 days at ₹3.00 per unit of consumption.
14. Calculate the area of cross section of a wire of length 2m, its
27. What is the electrical resistivity of a given material? What is its unit?
resistance is 25Ω and the resistivity of material of wire is 1.84*1 0 -
6 Ωm. 28. Calculate the resistance of a given metal wire of length 2m and area
15. Calculate the energy consumed by 120W toaster in 20 minutes. of cross-section 1.55 × 106 m² if the resistivity of the metal is taken to
16. What is resistance of conductors? Name two metals which are be 2.8 × 10-8 Ωm.
highly resistant. 29. When will current flow more easily through a thick wire or a thin
17. Why is tungsten metal used in bulbs but not in fuse wires? wire of the same material when connected to the same source? Why?
18. Define the terms Watt and Volt. 30. Discuss the heat generated while transferring 96000 coulombs of
19. An electric bulb which is connected to a 220 V generator and the
Charge in one hour through a potential difference of 50 V.
current is 2.5 A. Calculate the power of the bulb.
31. Two same resistors are first connected in series and then in parallel.
20. What is meant by the statement, “the resistance of a conductor is one
Find the ratio of equivalent resistance in both cases.
ohm”?
32. (a) Derive an expression or the equivalent resistance of three resistors
(b) Define electric power. Write an expression relating electric
R1, R2 and R3 connected in parallel.
power, potential difference and resistance.
(b) Find the minimum resistance that can be made using four
21. (a) Define the term volt
resistors, each of 20 ohm.
(b) State the relation between work, charge and potential difference
for an electric circuit.
Calculate the potential difference been the terminals of a battery if
100 joules of work is required to transfer 20 coulombs of charge from
one terminal of the battery of the other.
22. For the circuit diagram given below, calculate