Question 511 Mark
What do the following symbols mean in circuit diagrams?
Answer
View full question & answer→- Variable resistance.
- A closed plug key.
Questions · Page 2 of 3
Answer the questions.[Phy-1M]
Question 521 Mark
What does an electric circuit mean?
Answer
View full question & answer→An electric circuit consists of electric devices, switching devices, source of electricity, etc. that are connected by conducting wires.
Question 531 Mark
What determines the rate at which energy is delivered by a current?
Answer
View full question & answer→Electric power determines the rate at which energy is delivered by a current.
Question 541 Mark
What actually travels through the wires when you switch on a light`?
Answer
View full question & answer→Electrons.
Question 551 Mark
Two resistances X and Y are connected turn by turn:
- In parallel, and
- In series. In which case the resultant resistance will be less than either of the individual resistances?
Answer
View full question & answer→In case of parallel combination, the resultant resistance will be less than either of the individual resistances.
Question 561 Mark
Two exactly similar heating resistances are connected (i) in series, and (ii) in parallel, in two different circuits, one by one. If the same current is passed through both the combinations, is more heat obtained per minute when they are connected in series or when they are connected in parallel? Give reason for your answer.
Answer
View full question & answer→In series, because total resistance in series connection is more than that in parallel connection.
Question 571 Mark
The potential difference across wire is 75V and its electric resistance is $30\Omega$ Find out the electric current through the wire.
Answer
View full question & answer→Acoording to ohms law
$\text{v}=\text{ir}$
$75=\text{i}\times30$
$\text{i}=\frac{75}{30}=2.5$ ampere.
Question 581 Mark
The graph between V and 1 for a conductor is a straight line passing through the origin.
Which law is illustrated by such a graph?
What should remain constant in a statement of this law?
Which law is illustrated by such a graph?
What should remain constant in a statement of this law?
Answer
View full question & answer→- Ohm’s law.
- Temperature.
Question 591 Mark
The current passing through a room heater has been halved. What will happen to the heat produced by it?
Answer
View full question & answer→The heat produced by the heater will become one-fourth because heat produced is directly proportional to the square of the current.
Question 601 Mark
State whether a voltmeter has a high resistance or a low resistance. Give reason for your answer.
Answer
View full question & answer→Voltmeter has a high resistance so that it takes a negligible current from the circuit.
Question 611 Mark
State two factors on which the electrical energy consumed by an electrical appliance depends.
Answer
View full question & answer→Electrical energy consumed by an electrical appliance depends on:
- Power rating of the appliance.
- Time for which the appliance is used.
Question 621 Mark
State the SI unit of resistivity.
Answer
View full question & answer→Ohm meter.
Question 631 Mark
State the relation between work, charge and potential difference for an electric circuit.
Answer
View full question & answer→The difference in electric potential between two points is known as Potential difference.
The potential difference between two points in an electric field is defined as amount of work done in moving a unit charge from one point to other point. Potential difference = Work
Done/ Quantity of Chargemoved.
If W joules of work has to be done to move charge Q from one point to other point then potential difference V between two points is given by : $\text{V}=\frac{\text{W}}{\text{Q}}$
The potential difference between two points in an electric field is defined as amount of work done in moving a unit charge from one point to other point. Potential difference = Work
Done/ Quantity of Chargemoved.
If W joules of work has to be done to move charge Q from one point to other point then potential difference V between two points is given by : $\text{V}=\frac{\text{W}}{\text{Q}}$
Question 641 Mark
State the relation between potential difference, work done and charge moved.
Answer
View full question & answer→$\text{Potential difference} = \frac{\text{Work done}}{\text{Charge moved} }$
Question 651 Mark
State the factors on which the strength of electric current flowing in a given conductor depends.
Answer
View full question & answer→Strength of electric current flowing in a given conductor depends on:
- Potential difference across the ends of the conductor.
- Resistance of the conductor.
Question 661 Mark
Potential difference between points A and B in an electric field is 1V. Explain the above statement.
Answer
View full question & answer→It means that 1 J of work is being done to move a charge of 1 coulomb from point A to point B.
Question 671 Mark
Out of 60 W and 40 W lamps, which one has a higher electrical resistance when in use?
Answer
View full question & answer→Let us assume that the two bulbs are connected to the same supply. Let us say the value of the supply is voltage V. Now for 40W bulb Resistance of $40\text{W bulb}=\frac{\text{v}^2}{40}$ Similarly, Resistance of $60\text{W bulb}=\frac{\text{v}^2}{60}$
Since the denominator of first is less, hence the Resistance of 40W bulb will be MORE than the resistance of 60W bulb.
Question 681 Mark
One coulomb of charge flows through any cross-section of a conductor in 1 second. What is the current flowing through the conductor?
Answer
View full question & answer→1 ampere.
Question 691 Mark
Name two gases which are filled in filament type electric light bulbs.
Answer
View full question & answer→Argon and nitrogen.
Question 701 Mark
Name two effects produced by electric current.
Answer
View full question & answer→Two effects of produced by electric current are:
- Heating effect.
- Magnectic effect.
Question 711 Mark
Name the unit of electrical resistance and give its symbol.
Answer
View full question & answer→Unit of electrical resistance is ohm. its symbol is $\Omega$.
Question 721 Mark
Name the quantity whose unit is (i) kilowatt, and(ii) kilowatt-hour.
Answer
View full question & answer→- Electric power.
- Electric energy.
Question 731 Mark
Name the physical quantity whose unit is “ohm”.
Answer
View full question & answer→Electric resistance.
Question 741 Mark
Name the material which is used for making the heating element of an electric iron.
Answer
View full question & answer→Nichrome.
Question 751 Mark
Name the material which is used for making the filaments of an electric bulb.
Answer
View full question & answer→Tungsten is used for making the filaments of an electric bulb.
Question 761 Mark
Name the law which relates the current in a conductor to the potential difference across its ends.
Answer
View full question & answer→Ohm’s law.
Question 771 Mark
Name the law which is illustrated by the above V-I graph.
Answer
View full question & answer→Ohm’s law.
Question 781 Mark
Name the electrical property of a material whose symbol is “omega”.
Answer
View full question & answer→Resistance.
Question 791 Mark
Name the commercial unit of electric energy.
Answer
View full question & answer→Kilowatt-hour is the commercial unit of electric energy.
Question 801 Mark
Name a device which helps to maintain potential difference across a conductor (say, a bulb).
Answer
View full question & answer→Cell or battery helps to maintain potential difference across a conductor.
Question 811 Mark
Name a device that helps to measure the potential difference across a conductor.
Answer
View full question & answer→Voltmeter.
Question 821 Mark
Name a device that helps to maintain a potential difference across a conductor.
Answer
View full question & answer→Cell or battery eliminator.
Question 831 Mark
Mention the condition under which charges can move in a conductor.
Answer
View full question & answer→Charge can flow in a conductor only when there is a potential difference between two points in a circuit. potential difference causes charge to flow. And, we can maintain potential
difference in circuit with the help of a battery or cell.
difference in circuit with the help of a battery or cell.
Question 841 Mark
Keeping the resistance constant, the potential difference applied across the ends of a component is halved. By how much does the current change?
Answer
View full question & answer→V = R
Keeping R Constant, $\text{V}\propto\text{I}$
So, when V is halved, I also becomes half.
Keeping R Constant, $\text{V}\propto\text{I}$
So, when V is halved, I also becomes half.
Question 851 Mark
Keeping the potential difference constant, the resistance of a circuit is halved. By how much does the current change?
Answer
View full question & answer→V = R
$\text{I}=\frac{\text{V}}{\text{R}}$
Keeping V Constant $\text{I}\propto\frac{1}{\text{R}}$ So, when R is halved, I also becomes double.Question 861 Mark
Is electric current a scalar or vector quantity? Sate the smaller unit of current.
Answer
View full question & answer→Electric current is a SCALAR quantity! Sure it has magnitude and direction, but it still is a scalar quantity!
Question 871 Mark
In which direction does conventional current flow around a circuit?
Answer
View full question & answer→Conventional current flows from positive terminal of a battery to the negative terminal, through the outer circuit.
Question 881 Mark
In which direction do electrons flow?
Answer
View full question & answer→Electrons flow from negative terminal to positive terminal of the battery (opposite to the direction of conventional current).
Question 891 Mark
If the potential difference between the end of a wire of fixed resistance is doubled, by how much does the electric power increase?
Answer
View full question & answer→$\text{P}=\frac{\text{V}_2}{\text{R}}$
R is fixed.
V becomes double.
Now, $\text{P}=\frac{(2\text{V})2}{\text{R}}=\frac{4\text{V}_2}{\text{R}}$
So, the electric power becomes four times its previous value.
Question 901 Mark
If the length of a wire is doubled by taking more of wire, what happens to its resistance?
Answer
View full question & answer→Resistance also gets doubled.
Question 911 Mark
If the current passing through a conductor is doubled, what will be the change in heat produced?
Answer
View full question & answer→Heat produced is directly proportional to the square of current.
If current I is doubled, heat H will be four times.
If current I is doubled, heat H will be four times.
Question 921 Mark
If different resistors have the same value of electric potential across them, in which way they are connected to each other?
Answer
View full question & answer→The resistors are connected in parallel. In a parallel combination, the voltage across each resistor remains the same.
Question 931 Mark
If 20C of charge pass a point in a circuit in 1s, what current is flowing?
Answer
View full question & answer→Given, Q = 20C, t = 1s I = ? We know that:
$\text{I}=\frac{\text{Q}}{\text{T}}$
$\text{I}=\frac{20}{1}=20\text{A}$
Question 941 Mark
Identify the type of combination in which R1 and R2 are connected in the given circuit diagram.
Question 951 Mark
How should the two resistances of 2 ohms each be connencted so as to produce an equivalent resistance of 1 ohm?
Answer
View full question & answer→Since the resultant resistance is less than the individual resistances, so the resistances should be connected in parallel.
Question 961 Mark
How much work is done when one coulomb charge moves against a potential difference of 1 volt?
Answer
View full question & answer→Potential difference = 1V
Electricity
Charge moved = 1C
Work done = Potential difference × Charge moved
= 1 × 1 = 1J
Electricity
Charge moved = 1C
Work done = Potential difference × Charge moved
= 1 × 1 = 1J
Question 971 Mark
How much work is done in moving a charge of 2C across two points having a potential difference of 12V?
Answer
View full question & answer→Given,
Potential difference = 12V, Charge moved = 2C
We know that,
Work done= p.d. × charge moved
= 12 × 2
= 24 joules.
Potential difference = 12V, Charge moved = 2C
We know that,
Work done= p.d. × charge moved
= 12 × 2
= 24 joules.
Question 981 Mark
How many milliamperes are there in 1 ampere?
Answer
View full question & answer→1 amp = 10 milli amp.
Question 991 Mark
How many microamperes are there in 1 ampere?
Answer
View full question & answer→1amp = 106 micro amp.
Question 1001 Mark
How do you think the brightness of two lamps arranged in parallel compares with the brightness of two lamps arranged in series (both arrangements having one cell)?
Answer
View full question & answer→The brightness of two lamps arranged in parallel is much more those arranged in series.