Why is electrical wiring usually made from copper :
- ABecause copper is shiny.
- ✓Because copper conducts electricity.
- CBecause copper is not magnetic
- Dnone of these
Answer: B.
View full solution →Question types
Electricity question types
655 questions across 9 question groups — pick any mix to generate a Science paper with step-by-step answer keys.
655
Questions
9
Question groups
5
Question types
01
M.C.Q
181 Q→02Assertion - Reasoning (1 Marks)
19 Q→03Fill in the blank
10 Q→04True-False
3 Q→05[1 Mark Questions]
129 Q→06[2 Mark Questions]
144 Q→07[3 Mark Questions]
108 Q→08[5 marks Questions]
48 Q→09case /data -based (4 Marks)
13 Q→Sample Questions
Electricity questions
One sample from each question group in this chapter. Select any group above to see the full set with answer keys.
Which of the following option has no effect on an electric fuse wire?
- AIts specific resistance
- BIts radius
- ✓Its colour
- DCurrent flowing through it
Answer: C.
View full solution →The amount of heat produced in a wire depends on its material $-$
- ALength
- BThickness
- ✓Length and thickness
- DNone of these
Answer: C.
View full solution →The unit for expressing electric power is :
- AVolt.
- BJoule.
- CCoulomb.
- ✓Watt.
Answer: D.
View full solution →Which of the following gases are filled in electric bulbs?
- AHelium and Neon
- BNeon and Argon
- CArgon and Hydrogen
- ✓Argon and Nitrogen
Answer: D.
View full solution →In the following questions, a statement of Assertion is given by the corresponding statement of Reason. Of the statements, mark the correct answer as :
Assertion : Fuse wire must have high resistance and low melting point.
Reason : Fuse is used to protect the circuit.
Assertion : Fuse wire must have high resistance and low melting point.
Reason : Fuse is used to protect the circuit.
- AIf both Assertion and Reason are true and Reason is the correct explanation of Assertion.
- ✓If both Assertion and Reason are true, but Reason is not the correct explanation of Assertion.
- CIf Assertion is true, but Reason is false.
- DAssertion is false, but Reason is true.
Answer: B.
View full solution →For two statements are given$-$one labelled
Assertion $(A)$ and the other labelled
Reason $(R).$ Select the correct answer to these questions from the codes $(a), (b), (c)$ and $(d)$ as given below:
Assertion: Fuse wire must have high resistance and low melting point.
Reason: Fuse is used for small current flow only.
Assertion $(A)$ and the other labelled
Reason $(R).$ Select the correct answer to these questions from the codes $(a), (b), (c)$ and $(d)$ as given below:
Assertion: Fuse wire must have high resistance and low melting point.
Reason: Fuse is used for small current flow only.
- ABoth $A$ and $R$ are true, and $R$ is correct explanation of the assertion.
- BBoth $A$ and $R$ are true, but $R$ is not the correct explanation of the assertion.
- ✓$A$ is true, but $R$ is false.
- D$A$ is false, but $R$ is true.
Answer: C.
View full solution →For two statements are given-one labelled
Assertion $(A)$ and the other labelled
Reason $(R)$. Select the correct answer to these questions from the codes $(a), (b), (c)$ and $(d)$ as given below:
Assertion: Electron has a negative charge.
Reason: Electrons move always from a region of higher potential to a region of lower potential.
Assertion $(A)$ and the other labelled
Reason $(R)$. Select the correct answer to these questions from the codes $(a), (b), (c)$ and $(d)$ as given below:
Assertion: Electron has a negative charge.
Reason: Electrons move always from a region of higher potential to a region of lower potential.
- ABoth $A$ and $R$ are true, and $R$ is correct explanation of the assertion.
- BBoth $A$ and $R$ are true, but $R$ is not the correct explanation of the assertion.
- ✓$A$ is true, but $R$ is false.
- D$A$ is false, but $R$ is true.
Answer: C.
View full solution →For two statements are given $-$ one labelled Assertion $(A)$ and the other labelled Reason $(R)$. Select the correct answer to these questions from the codes $\ce{(a), (b), (c)}$ and $(d)$ as given below :
Assertion : A bird perches on a high $-$ power line and nothing happens to the bird.
Reason : The circuit is incomplete for the bird sitting on high-power line.
Assertion : A bird perches on a high $-$ power line and nothing happens to the bird.
Reason : The circuit is incomplete for the bird sitting on high-power line.
- ✓Both $A$ and $R$ are true and $R$ is correct explanation of the assertion.
- BBoth $A$ and $R$ are true but $R$ is not the correct explanation of the assertion.
- C$A$ is true but $R$ is false.
- D$A$ is false but $R$ is true.
Answer: A.
View full solution →For two statements are given $-$ one labelled Assertion $(A)$ and the other labelled Reason $(R)$. Select the correct answer to these questions from the codes $\ce{(a), (b), (c)}$ and $(d)$ as given below :
Assertion : The connecting wires are made of copper.
Reason : The electrical conductivity of copper is high.
Assertion : The connecting wires are made of copper.
Reason : The electrical conductivity of copper is high.
- ✓Both $A$ and $R$ are true, and $R$ is correct explanation of the assertion.
- BBoth $A$ and $R$ are true, but $R$ is not the correct explanation of the assertion.
- C$A$ is true, but $R$ is false.
- D$A$ is false, but $R$ is true.
Answer: A.
View full solution →Fuse wires are not connected in _______
Copper is a good _______ Plastic is an _______.
Tungsten is used for filaments in incandescent lamps as they do not _______ at high temperatures.
Current is measured in __________ using an __________ placed in __________ in a circuit.
Potential difference is measured in __________ by using a __________ placed in __________ across a component.
The nature of increase/decrease in resistivity of a metal and insulator are the same. [True/ False]
When resistors are connected in parallel, the sum of the currents in them is the current drawn from cell. [True/ False]
When resistors are connected in series, the sum of the currents in them is the current drawn from cell. [True/ False]
Name two devices which work on the heating effect of electric current.
What is the current in a circuit if the charge passing each point is 20C in 40s?
Why should the resistance of:
A voltmeter be very large?
A voltmeter be very large?
What happens to the resistance as the conductor is made thinner?
A resistance of 20 ohms has a current of 2 amperes flowing in it. What potential difference is there between its ends?
A piece of wire of resistance $R$ is cut into three equal parts. These parts are then connected in parallel. If the equivalent resistance of this parallel combination is $R_1$, what is the value of the ratio $R_1: R$ ?
View full solution →Explain why, the current that makes the heater element very hot, only slightly warms the connecting wires leading to the heater.
A heating coil has a resistance of 200Ω. At what rate will heat be produced in it when a current of 2.5A flows through it?
Calculate the resistance of an electric bulb which allows a 10 A current when connected to a 220 V power source.
What is an electric circuit? Distinguish between an open and a closed circuit.
(i) State the law that explains the heating effect of current with respect to the measurable properties in an electrical circuit.
(ii) List the factors on which the resistance of a conductor depends.
(ii) List the factors on which the resistance of a conductor depends.
For the circuit shown in the diagram given below:
Calculate:
Calculate:
- The total effective resistance of the circuit.
- The total current drawn from the battery.
- The value of current through each resistor.
- Define the term ‘volt’.
- State the relation between work, charge and potential difference for an electric circuit.
- Distinguish between the terms ‘overloading’ and ‘short-circuiting’ as used in domestic circuits.
- Why are the coils of electric toasters made of an alloy rather than a pure metal?
Two lamps, one rated 60 W at 220 V and the other 40 W at 220 V, are connected in parallel to the electric supply at 220 V.
- Draw a circuit diagram to show the connections.
- Calculate the current drawn from the electric supply.
- Calculate the total energy consumed by the two lamps together when they operate for one hour.
Explain with the help of a labelled circuit diagram how you will find the resistance of a combination of three resistors, of resistance $R_1, R_2$ and $R_3$, joined in parallel. Also mention how you will connect the ammeter and the voltmeter in the circuit when measuring the current in the circuit and the potential difference across one of the three resistors of the combination.
View full solution →Derive the expression for the heat produced due to a current ‘I’ flowing for a time interval ‘t’ through a resistor ‘R’ having a potential difference ‘V’ across its ends. With which name is the relation known? How much heat will an instrument of 12W produce in one minute if it is connected to a battery of 12V?
- What is meant by saying that the potential difference between two points is 1 volt? Name a device that helps to measure the potential difference across a conductor.
- Why does the connecting cord of an electric heater not glow hot while the heating element does?
- Electrical resistivities of some substances at $20^{0}\text{C}$ are given below:
| Silver | $1.60\times10^{-8} \Omega \text{ m}$ |
| Copper | $1.62\times10^{-8} \Omega \text{ m}$ |
| Tungsten | $5.20\times10^{-8} \Omega \text{ m}$ |
| Iron | $10.0\times10^{-8} \Omega \text{ m}$ |
| Mercury | $94.0\times10^{-8} \Omega \text{ m}$ |
| Nichrome | $100\times10^{-6} \Omega \text{ m}$ |
- Among silver and copper, which one is a better conductor? Why?
- Which material would you advise to be used in electrical heating devices? Why?
- Name an instrument that measures electric current in a circuit. Define the unit of electric current.
- What do the following symbols mean in circuit diagrams?
- An electric circuit consisting of a 0.5 m long nichrome wire XY, an ammeter, a voltmeter, four cells of 1.5 V each and a plug key was set up.
- Draw a diagram of this electric circuit to study the relation between the potential difference maintained between the points ‘X’ and ‘Y’ and the electric current flowing through XY.
- Following graph was plotted between V and I values:
What would be the values $\frac{\text{V}}{\text{I}}$of ratios when the potential difference is 0.8 V, 1.2 V and 1.6 V respectively? What conclusion do you draw from these values?
- What is scattering of light? Explain how the colour of the scattered light depends on the size of the scattering particles.
- Explain the reddish appearance of the Sun at sunrise or sunset. Why does it not appear red at noon?
Use the data in Table 12.2 to answer the following–
View full solution →- Which among iron and mercury is a better conductor?
- Which matcrial is the best conductor?
| - | Meterial | Resistivity ($\Omega$ m) |
| Conductors | Silver | $1.60 \times 10^{-8}$ |
| Copper | $1.60\times 10^{-8}$ | |
| Aluminium | $2.63\times 10^{-8}$ | |
| Tungsten | $5.20 \times 10^{-8}$ | |
| Nickel | $6.84\times 10^{-8}$ | |
| Iron | $10.0 \times 10^{-8}$ | |
| Chromoium | $12.9 \times 10^{-8}$ | |
| Mercury | $94.0\times 10^{-8}$ | |
| Manganese | $1.84 \times 10^{-6}$ | |
| Constant (alloy of Cu, Mn and Ni) | $49 \times 10^{-6}$ | |
| Alloys | Manganin (alloy of Cu, Mn and Ni) | $44 \times 10^{-6}$ |
| Nichrome (alloy of Ni, Cr, MN and Fe) | $100 \times 10^{-6}$ | |
| Glass | $10^{10}-10^{14}$ | |
| Insulators | Hard rubber | $10^{13}-10^{16}$ |
| Ebonite | $10^{15}-10^{17}$ | |
| Diamond | $10^{12}-10^{13}$ | |
| Paper (dry) | $10^{12}$ |
A boy noted the readings on his home’s electricity meter on Sunday at 8AM and again on Monday at 8AM (see figure below).
- What was the meter reading on Sunday?
- What was the meter reading on Monday?
- How many units of electricity have been used?
- In how much time these units have been used?
- If the rate is Rs. 5 per unit, what is the cost of electricity used during this time?
A student made an electric circuit shown here to measure the current through two lamps.
- Are the lamps in series or parallel?
- The student has made a mistake in this circuit. What is the mistake?
- Draw a circuit diagram to show the correct way to connect the circuit. Use the proper circuit symbols in your diagram.
Read the following and answer any three questions from (i) to (iv).The rate of flow of charge is called electric current. The SJ unit of electric current is Ampere (A). The direction of flow of current is always opposite to the direction of flow of electrons in the current. The electric potential is defined as the amount of work done in bringing a unit positive test charge from infinity to a point in the electric field. The amount of work done in bringing a unit positive test charge from one point to another point in an electric field is defined as potential difference.
$\text{V}_{\text{AB}}=\text{V}_{\text{B}}-\text{V}_\text{A}=\frac{\text{W}_{\text{BA}}}{\text{q}}$
The SJ unit of potential and potential difference is volt.
View full solution →$\text{V}_{\text{AB}}=\text{V}_{\text{B}}-\text{V}_\text{A}=\frac{\text{W}_{\text{BA}}}{\text{q}}$
The SJ unit of potential and potential difference is volt.
- The 2C of charge is flowing through a conductor in 100ms, the current in the circuit will?
- Define electric current? what is the SJ unit of electric current.
- The potential difference between the two terminals of battery, if 100 joules of work is required to transfer 20 coulombs of charge from one terminal of the battery to other will?
- a) Then number of electrons flowing per second in a conductor if I A current is passing through it?
b) The voltage can be written as.
Read the following and answer any three questions from (i) to (iv).The electrical energy consumed by an electrical appliance is given by the product of its power rating and the time for which it is used. The SI unit of electrical energy is Joule. Actually, Joule represents a very small quantity of energy, and therefore it is inconvenient to use where a large quantity of energy is involved. So for commercial purposes we use a bigger unit of electrical energy which is called kilowatt-hour. 1 kilowatt-hour is equal to $3.6 × 10^6$ joules of electrical energy.
View full solution →- The energy dissipated by the heater is E. When the time of operating the heater is doubled, the energy dissipated will?
- The power of a lamp is 60W. The energy consumed in 1 minute will?
- The electrical refrigerator rated 400W operates 8 hours a day. The cost of electrical energy is ₹ 5 per kWh. Find the cost of running the refrigerator for one day?
OR - Calculate the energy transformed by a 5A current flowing through a resistor of $2\Omega$ for 30 minutes?
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