Ohm's Law states that current through a conductor is directly proportional to voltage and inversely proportional to resistance: V = IR.

Difference between series and parallel circuits?

In series circuits, components are connected end-to-end and share the same current. In parallel circuits, components are connected across the same voltage and share current.

How to calculate electrical power?

Electrical power P can be calculated using P = VI, where V is voltage and I is current. Also, P = I²R or P = V²/R.

1. What is electric current?

Electric current is rate of flow of charge through a conductor.Unit:ampere (A). 1 A = 1 coulomb / second.

2. What is potential difference (p.d.)?

Potential difference between two points is work done in moving a unit charge from one point to the other.Unit:volt (V). 1 V = 1 joule / coulomb.

4. What factors affect resistance of a conductor?

Resistance depends on material (resistivityρ), lengthl(∝ l) and cross-sectional areaA(∝ 1/A). Formula:R = ρ l / A. Temperature also affects resistance for most materials.

5. What is resistivity?

Resistivity (ρ) is a material's intrinsic property indicating how strongly it opposes current. Unit: ohm·metre (Ω·m). Lowρ→ good conductor.

6. How do resistors add in series?

In series: same current through each resistor. Total resistanceR_eq = R1 + R2 + R3 + .... Voltage divides across resistors.

7. How do resistors add in parallel?

In parallel: same potential difference across each resistor. Total:1/R_eq = 1/R1 + 1/R2 + .... For two resistors:R_eq = (R1·R2)/(R1+R2).

8. Key differences between series and parallel circuits?

Emf (ε) is the energy supplied per unit charge by a source (open-circuit voltage). Terminal voltage is emf minus drop across internal resistance when current flows:V = ε - I r.

Electricity | Class 10 Science Notes

📘 Introduction

This chapter covers Electricity, explaining Ohm's Law, series & parallel circuits, current, voltage, resistance, and electrical power. Essential for NEET, SSC, Railway, and Police Bharti preparation and Class 10 board exams.

🔹 Key Concepts

Electric Current (I): Flow of electric charge
Voltage (V): Electric potential difference
Resistance (R): Opposition to current
Ohm's Law: V = IR
Series Circuits: Same current through all components
Parallel Circuits: Same voltage across all components
Power (P): P = VI = I²R = V²/R

📊 Chapter Summary Table

Concept	Formula / Definition	Use
Ohm's Law	V = IR	Calculates current, voltage, resistance
Series Circuit	I same, V adds	Total resistance adds up
Parallel Circuit	V same, I adds	Total resistance decreases
Electrical Power	P = VI = I²R = V²/R	Measures energy consumption

🧮 Practice Questions

State Ohm's Law. ➡ Show Answer
Current through a conductor is directly proportional to voltage and inversely proportional to resistance: V = IR.
Difference between series and parallel circuits. ➡ Show Answer
Series: Same current, voltage divides. Parallel: Same voltage, current divides among branches.
Calculate electrical power in terms of I, R and V. ➡ Show Answer
P = VI = I²R = V²/R

Current & Voltage Resistance & Ohm Circuits Safety

NCERT Class 10 — Electricity

📘 Introduction

🔹 Key Concepts

📊 Chapter Summary Table

🧮 Practice Questions

1. What is electric current?

2. What is potential difference (p.d.)?

3. State Ohm's law.

4. What factors affect resistance of a conductor?

5. What is resistivity?

6. How do resistors add in series?

7. How do resistors add in parallel?

8. Key differences between series and parallel circuits?

9. What is electromotive force (emf) and terminal voltage?

10. What is internal resistance and its effect?

11. Define electric power and give formulas.

12. How is electrical energy consumption measured and billed?

13. What is the heating effect of electric current?

14. What is a fuse and why is it used?

15. What are Live, Neutral and Earth wires and their purposes?

16. Why is earthing important?

17. How are ammeters and voltmeters connected in a circuit?

18. State Kirchhoff's laws (brief).

19. How does an electricity meter measure energy consumption?

20. Why are household electrical circuits wired in parallel?

21. What is a short circuit and why is it dangerous?

22. What is an MCB and how is it different from a fuse?

23. How to simplify and find equivalent resistance in circuits?

24. What is a potential divider (voltage divider)?

25. Give examples of conductors and insulators.

26. How does conduction happen in metals (brief)?

27. What is an LDR (Light Dependent Resistor)?

28. Why is nichrome used in heating elements?

29. Tips to reduce electrical energy consumption at home?

30. How is earthing implemented practically?

31. (Overview) How is earthing treated in building supply systems?

32. Why transmit electrical power at high voltages?

33. What is a transformer (brief)?

34. What is a lightning conductor and how is it different from earthing?

35. How does temperature affect resistance?

36. What is a superconductor (brief)?

37. Worked example: A 12 V battery connected to two resistors 3 Ω & 6 Ω in series — find current and voltage across each.

38. Worked example: Two resistors 4 Ω and 12 Ω in parallel across 12 V — find total current and current through each.

39. How to choose a fuse rating for an appliance?

40. What is an RCCB (Residual Current Circuit Breaker)?

41. Why are bulbs in homes wired in parallel instead of series?

42. What happens if live wire touches appliance body (metal)?

43. What is a solar cell (brief)?

44. What are primary & secondary cells? Examples.

45. Practical electrical safety tips for home?

46. Examples of appliances that use heating effect and how they work?

47. How does an electric bell work (brief EM principle)?

48. State Lenz's law (brief) and its significance?

49. Quick formula sheet (Electricity — high yield)

50. Final summary: Key points for Electricity (quick revision)