A Collection of Questions from Class X (10) Cbse Physics

A COLLECTION OF QUESTIONS FROM CLASS X (10) CBSE PHYSICS
REQUIRING HIGHER ORDER THINKING SKILLS

(Includes questions from sample paper issued by CBSE)

1. Two students perform the experiments on series and parallel combinations of two given
resistors R1 and R2 and plot the following V-I graphs.

Which of the graphs is (are) correctly labelled in terms of the words ‘series’ and parallel’
Justify your answer.

2. You are given following current-time graphs from two different sources:

(i) Name the type of current in two cases.
(ii) Identify any one source for each type of these currents.
(iii) What is the frequency of current in case II in India?
(iv) Use above graphs to write two difference between the current in two cases.

3. Two metallic wires A and B are connected in parallel. Wire A has length l and radius r, wire
B has a length 2l and radius 2r. Compute the ratio of the total resistance of parallel
combination and the resistance of wire A.

4. A student performs an experiment to study the magnetic effect of current around a current
carrying straight conductor. He reports that
(i) the direction of deflection of the north pole of a compass needle kept at a given point
near the conductor remains unaffected even when the terminals of the battery sending
current in the wire are inter changed.
(ii) for a given battery, the degree of deflection of a N-pole decreases when the compass
is kept at a point farther away from the conductor.
Which of the above observations of the student is incorrect and why?

5. A beam of white light falling on a glass prism gets split up into seven colours marked 1 to 7 as shown in the diagram.
A student makes the following statements about the spectrum observed on the screen.

a) The colours at positions marked 3 and 5 are similar to the colour of the sky and the core of a hard boiled egg respectively.
Is the above statement made by the student correct or incorrect? Justify.
b) Which two positions correspond closely to the colour of
(i) a solution of potassium permanganate?
(ii) ‘danger’ or stop signal lights?

6. a) The electric power consumed by a device may be calculated by using either of the two expressions . The first expression indicates that it is directly proportional to R whereas the second expression indicates inverse proportionality. How can the seemingly different dependence of P on R in these expressions be explained?
b) Explain the following:
(i) Why is tungsten used almost exclusively for filament of electric lamps?
(ii) Why are copper and aluminium wires usually used for electricity transmission?

7. You are give three resistors of 10 Ω, 10 Ω and 20 Ω, a battery of emf 2.5V, a key, an ammeter and a voltmeter. Draw a circuit diagram showing the correct connections of all given components such that the voltmeter gives a reading of 2.0V.

8. A person is able to see objects clearly only when these are lying at distances between 50cm and 300cm from his eye.
a) What kind of defects of vision he is suffering from?
b) What kind of lenses will be required to increase his range of vision from 25cm to infinity? Explain briefly.

9. On what principle does a solar heating device operate? Draw a labeled schematic diagram for a solar cooker. The solar constant at a place is 1.4 kW/m2. How much solar energy will be received at this place per second over an area of 5 m2?

10. A parallel combination of three resistances take a current of 7.5 A from a 30 V battery. If two of the resistance values are 10 Ω and 12 Ω, find the third.

11. When will the force experienced by a current carrying conductor be maximum? State the rule used to calculate the same.

12. The following table gives the values of refractive indices of a few liquid media:

S.No. / 1 / 2 / 3 / 4 / 5
Medium / Alcohol / Benzene / Kerosene / Water / Turpentine
Refractive index / 1.36 / 1.50 / 1.44 / 1.33 / 1.47

Light passes through these media one by one. Arrange the given media in the increasing order of the speed of light.

13. Draw the pattern of magnetic field lines of a current carrying circular loop. What does the pattern of field lines inside the circular loop indicate? On what factor does the strength of the magnetic field in a circular coil depends?

14. A convex mirror used for rear-view on an automobile has a radius of curvature of 3.00 m. If a bus is located at 5.00 m from this mirror, find the position, nature and size of the image.

15. In a household electric circuit different appliances are connected in parallel to one another. Give two reasons.
Two electric lamps rated 100W; 220V and 25W; 220V are connected in parallel to a 220V supply. Calculate the total electric current flowing through the circuit.

16. Refractive index of water is 4/3 and that of the glass is 3/2 with regard to air. What is the refractive index of glass with respect to the water?

17. An object 4 cm high is placed at a distance of 10 cm from a convex lens of focal length 20 cm. (a) Draw ray diagram for formation of the image; (b) Find the position, nature and size of the image.

18. (i) State the law that governs the strength of the current passing through a metallic conductor when a potential difference is applied across its ends. Illustrate this law graphically.
(ii) Three resistors each of resistance 10 W are connected, in turn, to obtain
(a) Minimum resistance and (b) Maximum resistance
Compute

The effective resistance in each case.
The ratio of the minimum to the maximum resistances so obtained.

19. (i) State the law that governs the amount of heat produced in a metallic conductor when electric current is passed through it for a given time. Express this law mathematically.
(ii) Two resistors of resistances 2 W and 4 W are, in turn, connected
(a) In series and (b) In parallel to a given battery for the same time interval.
Compute the ratio of the total quantity of heat produced in the combination in the two cases.

20. Why is series arrangement not satisfied for domestic circuit?

21. A nichrome wire has a resistance of 5Ω. Find the resistance of another nichrome wire, whose length is four times and area of cross section is three times the first wire.

22. Give reason for the following:

The sky appears to be blue during daytime to a person on earth.
The sun appears circular during evening hours.
The stars appear to twinkle.
The planets do not twinkle.
Danger signals are made of red colour.

23. Two round wires, A&B drawn out of the same metal and of same cross section have their lengths in the ratios 1:3 If a potential difference of 12 volts exist between the ends of wires, find the ratio of the current flowing through them

24. Two resistors of the resistances 2 W each are connected in series to a set of resistances of resistances 2 W each connected in parallel such that total resistance of the system is 4.5 W. Find the total number of resistances connected in parallel.

25. A person’s far point is 3 meters and his near point is 50 c.m. Find the nature, power of the lens he must use to (a) read a book kept at the least distance of distinct vision and,(b) to see birds flying at a large distance.

26. A ray of light passes through a glass slab of thickness 2 c.m. The refractive index of glass is 7/5. What would be the angle between incident ray and the emergent ray?

27. (i) State Fleming’s Left Hand Rule. Explain an activity to show the relation illustrated by this rule. Draw a diagram to support your answer.

(ii) What is over loading and short – circuiting?

NUMERICALS ON ELECTRICITY

The current passing through a room heater has been halved. What will happen to the heat produced by it?
An electric iron of resistance 20 ohm draws a current of 5 amperes. Calculate the heat produced in 30 seconds.
An electric heater of resistance 8 ohm takes a current of 15 A from the mains supply line. Calculate the rate at which heat is developed in the heater.
A resistance of 40 ohms and one of 60 ohms are arranged in series across 220 volt supply. Find the heat in joules produced by this combination in half a minute.
A resistance of 25 ohm is connected to a 12 V battery. Calculate the heat energy in joules generated per minute.
100 joules of heat is produced per second in a 4 ohm resistor. What is the potential difference across the resistor?
An electric iron is connected to the mains power supply of 220 V. When the electric iron is adjusted at minimum heating’ it consumes a power of 360 W but at ‘maximum heating’ it takes a power of 840 W. Calculate the current and resistance in each case.
Ten bulbs are connected in a series circuit to a power supply line. Ten identical bulbs are connected in a parallel circuit to an identical power supply line.
Which circuit would have the highest voltage across each bulb
In which circuit would the bulbs be brighter?
In which circuit, if one bulb blows out, all others will stop glowing?
Which circuit would have less current in it?
Calculate the cost of operating a heater of 500 W for 20 hours at the rate of Rs. 3.90 per unit.
Which has a greater resistance, a 100 watt bulb or a 60 watt bulb?
How much energy is consumed when a current of 5 amperes flows through the filament (or element) of a heater having resistance of 100 ohms for two hours? Express it in joules.
An electric bulb is rated at 220 V, 100 W. What is its resistance?
An electric bulb is connected to a 220 V power supply line. If the bulb draws a current of 0.5 A, calculate the power of the bulb.
In which of the following cases more electrical energy is consumed per hour?
A current of 1 ampere passed through a resistance of 300 ohms
A current of 2 amperes passed through a resistance of 100 ohms.
Electric kettle rated at 220 V, 2.2 kW, works for 3 hours. Find he energy consumed and the current drawn. W
In a house two 60 W electric bulbs are lighted for 4 hours, and three 100 W bulbs for 5 hours everyday. Calculate the electric energy consumed in 30 days.
If the potential difference between the ends of a wire of fixed resistance is doubled, by how much does the electric power increase?
A bulb is rated as 250 V; 0.4 A. Find its : (i) power, and (ii) resistance.
For a heater rated at 4 kW and 220 V, calculate (a) the current, b) the resistance of the heater, ) the energy consumed in 2 hours, and d) the cost if 1 kWh is priced at Rs. 4.60.
An electric motor takes 5 amperes current from a 220 volt supply line. Calculate the power of the motor arid electrical energy consumed by it in 2 hours.
Which uses more energy: a 250 W TV set in 1 hour or a 1200 W Toaster in 10 minutes?
An electric bulb is rated as 10 W, 220 V. How many of these bulbs can be connected in parallel across the two wires of 220 V supply line if the maximum current which can be drawn is 5 A.
How much work is done in moving a charge of 2 coulombs from a point at 118 volts to a point at 128 volts?
What possible values of resultant resistance one can get by combining two resistances, one of value 2 ohm and the other 6 ohm?
If 3 resistances of 3 ohm each are connected in parallel, what will be their total resistance?
If five resistances, each of value 0.2 ohm, are connected in series, what will be the resultant resistance?
Four resistances of 16 ohms each are connected in parallel. Four such combinations are connected in series. What is the total resistance?
An electric bulb of resistance 20 and a resistance wire of 4 are connected in series with a 6 V battery. Draw the circuit diagram and calculate (i)the total resistance of the circuit.(ii) Current through the circuit. (iii)Potential difference across the electric bulb.(iv)Potential difference across the resistance wire.
How will you connect three resistors of 2 ohm, 3 ohm and 5 ohm respectively so as to obtain a resultant resistance of 2.5 ohm? Draw the diagram to show the arrangement.
How will you connect three resistors of resistances 2ohm, 3 ohm and 6 ohm to obtain a total resistance of: (a) 4 ohm, and (b) 1 ohm?
A wire of resistance R is cut into five equal pieces. These five pieces of wire are then connected in parallel. If the resultant resistance of this combination be R then the ratio of resultant to the original will be?
A copper wire has a diameter of 0.5 mm and resistivity of 1.6 x 10 m.
What will be the length of this wire to make its resistance 10 2ohm?
How much does the resistance change if the diameter is doubled?
An electric heater which is connected to a 220 V supply line has two resistance coils A and B of 24 resistances each. These coils can be used separately (one at a time), in series or in parallel. Calculate the current drawn when
Only one coil A is used.
Coils A and B are used in series.
Coils A and B are used in parallel.
If the length of a wire is doubled by taking more of wire, what happens to its resistance?
How does the resistance of a wire change when
Its length is tripled?
Its diameter is tripled?
Its material is changed to one whose resistivity is three times?
How much energy is given to each coulomb of charge passing through a 6 V battery?
The potential difference between the terminals of an electric iron is 240 V and the current is 5.0 A. What is the resistance of the electric iron?
A potential difference of 20 volts is applied across the ends of a resistance of 5 ohms. What current will flow in the resistance?
A resistance of 20 ohms has a current of 2 amperes flowing in it. What potential difference is there between its ends?
A current of 5 amperes flows through a wire whose ends are at a potential difference of 3 volts. Calculate the resistance of the wire.
The resistance of an electric lamp filament is 230 ohms. The lamp is switched on when the line voltage is 115 volts. What is the current in the lamp circuit?
What is the potential difference between the ends of a conductor of 16 ohm resistance, when a current of 1.5 A flows through it?
Calculate the work done in moving a charge of 4 coulombs from a point at 220 volts to another point at 230 volts.
What is the potential difference between the terminals of a battery if 250 joules of work is required to transfer 20 coulombs of charge from one terminal of the battery to the other?
How much work is done in moving a charge of 2 C across two points having a potential difference of 12 V?
An electric bulb draws a current of 0.25 A for 20 minutes. Calculate the amount of electric charge that flows through the circuit.
A radio set draws a current of 0.36 A for 15 minutes. Calculate the amount of electric charge that flows through the circuit.
Potential difference between two points of a wire carrying 2 ampere current is 0.1 volt. Calculate the resistance between these points.
A simple electric circuit has a 24 V battery and a resistor of 60 ohms. What will be the current in the circuit? The resistance of the connecting wires is negligible.
A wire of resistance R is cut into five equal pieces. These five pieces of wire are then connected in parallel. If the resultant resistance of this combination be R then the ratio of resultant to the original will be?