Exercise Solutions Available
Step-by-step answers for all textbook questions in this chapter
Electricity — Complete Exercise Solutions
Use this page alongside the official Samacheer Kalvi 6th Science Term 2, Chapter 2: Electricity textbook. Solve each exercise on your own first, then check your answers below.
I. Choose the Appropriate Answer (MCQ)
Q1. The device which converts chemical energy into electrical energy is
- (a) fan
- (b) solar cell
- (c) cell ✓
- (d) television
A cell converts stored chemical energy into electrical energy. A fan uses electrical energy, a solar cell converts light energy (not chemical), and a television consumes electrical energy.
Q2. Electricity is produced in
- (a) transformer
- (b) power station ✓
- (c) electric wire
- (d) television
Power stations (thermal, hydel, nuclear, wind) generate electricity. Transformers only change voltage; wires carry it; televisions consume it.
Q3. Choose the correct symbol for a battery
Q4. In which circuit does the bulb glow?
Q5. ____________ is a good conductor
- (a) silver ✓
- (b) wood
- (c) rubber
- (d) plastic
Silver is one of the best conductors of electricity. Wood, rubber, and plastic are insulators — they do not allow electric current to pass through them.
II. Fill in the Blanks
1. ____________ are the materials which allow electric current to pass through them.
Conductors (like copper, aluminium, silver) permit the free flow of electric charges through them.
2. Flow of electricity through a closed circuit is ____________
A closed circuit provides an unbroken path for current to flow from the positive terminal, through the components, and back to the negative terminal.
3. ____________ is the device used to close or open an electric circuit.
A switch (also called a key in circuit diagrams) lets you make or break the circuit, controlling whether current flows.
4. The long perpendicular line in the electrical symbol represents its ____________ terminal.
In the standard symbol for an electric cell, the longer line represents the positive (+) terminal and the shorter, thicker line represents the negative (-) terminal.
5. The combination of two or more cells is called a ____________
When two or more cells are connected together (positive of one to negative of the next), they form a battery. The battery provides a higher voltage than a single cell.
III. True or False (with corrections)
Q1. In a parallel circuit, the electricity has more than one path.
In a parallel circuit, current can flow through multiple branches simultaneously. If one branch is broken, current still flows through the others.
Q2. To make a battery of two cells, the negative terminal of one cell is connected to the negative terminal of the other cell.
Correction: To make a battery, the negative terminal of one cell is connected to the positive terminal of the other cell. Connecting negative-to-negative or positive-to-positive does not form a proper battery.
Q3. The switch is used to close or open an electric circuit.
A switch is a device that can be opened (to break the circuit) or closed (to complete the circuit), thereby controlling the flow of current.
Q4. Pure water is a good conductor of electricity.
Correction: Impure water (water containing dissolved salts/minerals) is a good conductor of electricity. Pure (distilled) water is actually a poor conductor because it lacks free ions.
Q5. The secondary cell can be used only once.
Correction: Primary cells can be used only once. Secondary cells (also called rechargeable cells) can be recharged and used many times. Examples: lead-acid battery in cars, lithium-ion batteries in phones.
IV. Match the Following
| Column A | Column B |
|---|---|
| Cell | Converts chemical energy into electrical energy |
| Battery | Combination of two or more cells |
| Switch | Opens or closes an electric circuit |
| Conductor | Allows electric current to pass through |
| Insulator | Does not allow electric current to pass through |
| Bulb | Converts electrical energy into light energy |
V. Arrange in Sequence
Correct sequence to set up a simple electric circuit:
1. Take an electric cell — it provides the energy source. 2. Connect a wire from the positive terminal of the cell to one terminal of the bulb holder. 3. Connect a second wire from the other terminal of the bulb holder. 4. Connect the free end of the second wire to the negative terminal of the cell. 5. The bulb glows — current flows through the closed circuit.
If a switch is used, place it anywhere in the circuit loop. The bulb glows only when the switch is closed.
VI. Very Short Answers
Q1. In the given circuit diagram, which switch(es) should be closed so that only bulb A glows?
Q2. Assertion (A): It is very easy for our body to receive an electric shock. Reason (R): Human body is a good conductor of electricity.
- (a) Both A and R are correct and R is the correct explanation for A ✓
- (b) A is correct, but R is not the correct explanation for A.
- (c) A is wrong but R is correct.
- (d) Both A and R are correct and R is not the correct explanation for A.
Q3. Can you produce electricity from a lemon?
Q4. Identify the conductor from the following figures.
Q5. What type of circuit is there in a torchlight?
Q6. Circle the odd one out. Give a reason: Switch, Bulb, Battery, Generator.
- Switch, Bulb, Battery are all components used in a simple electric circuit.
- Generator is a device that produces (generates) electricity on a large scale — it is not a basic circuit component.
VII. Short Answers
Q1. Draw the circuit diagram for a series connection.
A series circuit connects all components in a single path:
- Cell/Battery at one end (long line = positive terminal, short thick line = negative terminal)
- Switch (Key) in the path
- Two or more bulbs connected one after the other
- Wires connecting everything in a single closed loop
In a series circuit, if one bulb fuses, the entire circuit breaks and all bulbs stop glowing.
Q2. Can the cell used in the clock give us an electric shock? Justify your answer.
Q3. Silver is a good conductor but it is not preferred for making electric wires. Why?
VIII. Detailed Answers
Q1. What is the source of electricity? Explain the various power stations in India.
Source of electricity: Any device or setup from which electricity is produced is called a source of electricity. Examples include cells, batteries, and power stations.
Types of power stations in India:
1. Thermal Power Stations
- Burn coal, diesel, or gas to produce heat.
- Heat converts water into steam; steam rotates a turbine.
- The turbine rotates a coil of wire between electromagnets, producing electricity by electromagnetic induction.
- Energy conversion: Chemical energy (fuel) → Heat energy → Kinetic energy (steam/turbine) → Electrical energy.
- Examples: Neyveli Lignite Corporation (Tamil Nadu), Talcher (Odisha).
2. Hydel (Hydroelectric) Power Stations
- Water stored in dams is released to flow through turbines.
- The flowing water rotates the turbine, which generates electricity.
- Energy conversion: Potential energy (stored water) → Kinetic energy (flowing water) → Electrical energy.
- Advantages: Long economic life, low operating cost, renewable.
- Examples: Mettur Dam (Tamil Nadu), Bhakra Nangal (Punjab).
3. Atomic (Nuclear) Power Stations
- Nuclear fuel (uranium) undergoes fission, releasing enormous heat.
- This heat boils water to produce steam; steam drives the turbine.
- Energy conversion: Nuclear energy → Heat energy → Kinetic energy → Electrical energy.
- Examples: Kudankulam (Tamil Nadu), Kalpakkam (Tamil Nadu), Tarapur (Maharashtra).
4. Wind Mills (Wind Power Stations)
- Wind rotates the blades of a windmill (turbine).
- The turbine drives a generator to produce electricity.
- Energy conversion: Kinetic energy (wind) → Electrical energy.
- Advantages: Clean, renewable, no fuel cost.
- Examples: Muppandal Wind Farm (Tamil Nadu) — one of the largest in Asia.
Q2. Tabulate the different components of an electric circuit and their respective symbols.
| Component | Symbol Description |
|---|---|
| Electric cell | One long line (positive terminal) and one short thick line (negative terminal) |
| Battery | Two or more pairs of long and short parallel lines |
| Bulb | A circle with a cross (X) inside it |
| Switch (Key) — Open | A line with a gap and a tilted line not touching the other terminal |
| Switch (Key) — Closed | A line with no gap, tilted line touching the other terminal |
| Connecting wire | A straight line |
| Resistor | A zigzag line |
| Ammeter | A circle with the letter A inside |
| Voltmeter | A circle with the letter V inside |
Remember: The long line always represents the positive terminal and the short thick line represents the negative terminal of a cell.
Q3. Write short notes on conductors and insulators.
Conductors:
- Materials that allow electric current to pass through them easily.
- They have free electrons that move and carry charge.
- Examples: Copper, aluminium, iron, silver, gold, impure water, human body, earth.
- Uses: Making electric wires (copper, aluminium), cooking utensils, electrical contacts.
Insulators:
- Materials that do not allow electric current to pass through them.
- They lack free electrons, so charge cannot flow through them.
- Examples: Rubber, plastic, glass, wood, ebonite, china clay, air, pure water, mica.
- Uses: Covering electric wires (rubber/plastic insulation), handles of electrical tools, switch boxes.
Key point: Conductors and insulators work together — a copper wire (conductor) carries current, while its rubber coating (insulator) protects us from electric shock.
IX. Higher Order Thinking Skills (HOTS)
Q1. Rahul wants to make an electric circuit. He has a bulb, two wires, a safety pin, and a piece of copper. He does not have any electric cell or battery. He uses a lemon instead of a battery. Will the bulb glow?
Steps to make the lemon battery: 1. Squeeze the lemon gently without breaking the skin (this releases the juice inside, which acts as electrolyte). 2. Insert a copper piece into one side of the lemon — this acts as the positive terminal. 3. Insert an iron nail or hairpin into the other side — this acts as the negative terminal. 4. Connect one wire from the copper piece to one terminal of the bulb. 5. Connect the other wire from the iron nail to the other terminal of the bulb. 6. The chemical reaction between the lemon juice and the two different metals produces a small electric current, and the bulb glows.
Note: The glow will be dim because a single lemon produces only about 0.8–1.0 V. Using two or more lemons connected as a battery produces more voltage and a brighter glow.
Word Grid Activity
Ten words found in the word grid:
| Conductors | Insulators |
|---|---|
| Aluminium | Wood |
| Copper | Plastic |
| Iron | Rubber |
| Earth | Glass |
| Seawater | Eraser |
Common Mistakes
1. Connecting cells positive-to-positive or negative-to-negative in a battery. Always connect the positive terminal of one cell to the negative terminal of the next cell. Wrong connections cancel out the voltage.
2. Saying "pure water is a good conductor." Pure (distilled) water is a poor conductor. Only impure water (water with dissolved salts/minerals) conducts electricity. Tap water, seawater, and rainwater are conductors.
3. Confusing primary and secondary cells. Primary cells can be used only once (e.g., dry cells used in torches, clocks). Secondary cells are rechargeable and can be used many times (e.g., car batteries, mobile phone batteries).
4. Thinking a bulb glows in an open circuit. Current flows only in a closed (complete) circuit. If there is a break anywhere — a disconnected wire, an open switch, or a fused bulb — current stops and the bulb does not glow.
5. Confusing series and parallel circuits. In a series circuit, current has only one path — if one component fails, the whole circuit stops. In a parallel circuit, current has multiple paths — if one branch breaks, others still work.
6. Assuming silver should be used for electric wires. Silver is the best conductor but is far too expensive. Copper is the preferred material for wires because it offers excellent conductivity at a much lower cost.
7. Forgetting that the human body is a conductor. Our body contains water and electrolytes, making it a good conductor. This is why we receive electric shocks — current passes through our body to the ground.
Exam Checklist
- [ ] Define electric cell and identify its positive and negative terminals
- [ ] Draw and interpret circuit symbols (cell, battery, bulb, switch, wire, ammeter, voltmeter)
- [ ] Differentiate between open and closed circuits
- [ ] Explain the difference between series and parallel circuits
- [ ] Define conductors and insulators with at least 5 examples of each
- [ ] State why pure water is a poor conductor but impure water is a good conductor
- [ ] Distinguish between primary cells and secondary cells
- [ ] Explain how a lemon can act as a cell (HOTS)
- [ ] List the four types of power stations in India with energy conversions
- [ ] Explain why copper (not silver) is used for electric wires
- [ ] State why the human body receives electric shocks (body is a conductor)
- [ ] Correctly connect cells to form a battery (positive to negative)