1. What is electricity?
Electricity is the flow of electric charge through a conductor.
2. What is electric current?
It is the rate of flow of electric charge (I
3. What is the SI unit of electric current?
The SI unit is ampere (A).
4. What is charge?
Charge is a property of matter causing electric forces.
5. What is the SI unit of charge?
The SI unit is coulomb (C).
6. What carries electric current in metals?
Free electrons carry current in metallic conductors.
7. What is 1 ampere?
1 A is 1 coulomb of charge flowing per second.
8. What is the direction of electric current?
It flows from positive to negative, conventionally.
9. What is the actual direction of electron flow?
Electrons flow from negative to positive.
10. What is a conductor?
A material that allows easy flow of electric current.
11. What is an insulator?
A material that resists the flow of electric current.
12. What is the formula for charge?
Charge (Q)
13. How much charge flows if 2 A flows for 5 s?
Q
14. What is a source of electric current?
A battery or generator provides electric current.
15. What is direct current (DC)?
Current that flows in one direction only.
16. What is alternating current (AC)?
Current that reverses direction periodically.
17. What device measures electric current?
An ammeter measures electric current.
18. How is an ammeter connected in a circuit?
It is connected in series with the circuit.
19. What is the unit of time in current calculations?
The SI unit of time is seconds (s).
20. What is the smallest unit of charge?
The charge of an electron, 1.6 × 10⁻¹⁹ C.
21. What is potential difference?
It is the work done per unit charge (V
22. What is the SI unit of potential difference?
The SI unit is volt (V).
23. What is 1 volt?
1 V is 1 joule of work per coulomb of charge.
24. What causes potential difference?
A difference in electric potential energy causes it.
25. What device maintains potential difference?
A battery maintains potential difference in a circuit.
26. What is electromotive force (EMF)?
EMF is the energy supplied per unit charge by a source.
27. What is the unit of EMF?
It is measured in volts (V).
28. What device measures potential difference?
A voltmeter measures potential difference.
29. How is a voltmeter connected in a circuit?
It is connected in parallel across components.
30. What is terminal voltage?
The potential difference across a battery’s terminals.
31. What happens to potential difference in an open circuit?
It equals the EMF as no current flows.
32. What is the work done if V
W
33. What is the potential difference if 20 J moves 4 C?
V
34. What is electric potential?
The potential energy per unit charge at a point.
35. What is the unit of electric potential?
It is volt (V), same as potential difference.
36. What is a cell in electricity?
A device converting chemical energy to electrical energy.
37. What is the role of a battery?
It provides a steady potential difference for current.
38. What is a closed circuit?
A complete path allowing current to flow.
39. What is an open circuit?
A broken path stopping current flow.
40. What is the symbol for potential difference?
It is denoted by V in formulas.
41. What is Ohm’s Law?
Voltage equals current times resistance (V
42. What is resistance?
It is the opposition to the flow of electric current.
43. What is the SI unit of resistance?
The SI unit is ohm (Ω).
44. What is 1 ohm?
1 Ω is 1 volt per ampere of current.
45. What factors affect resistance?
Length, area, material, and temperature affect resistance.
46. How does length affect resistance?
Resistance increases with the length of the conductor.
47. How does cross-sectional area affect resistance?
Resistance decreases with a larger area.
48. What is resistivity?
It is the resistance per unit length and area of a material.
49. What is the SI unit of resistivity?
It is ohm-meter (Ω·m).
50. What is the formula for resistance?
R
51. What is the resistivity of copper?
It is about 1.68 × 10⁻⁸ Ω·m, very low.
52. What is a conductor’s resistance if V
53. What is the current if V
I
54. What is the voltage if I
55. What is a non-ohmic conductor?
A material where V and I are not directly proportional.
56. What is an ohmic conductor?
A material obeying Ohm’s Law with a linear V-I graph.
57. What is the V-I graph for an ohmic conductor?
It is a straight line passing through the origin.
58. What is the slope of the V-I graph?
The slope represents resistance (R
59. What happens to resistance with temperature?
Resistance increases with temperature in conductors.
60. What is the resistance of an insulator?
It is extremely high, preventing current flow.
61. What is a superconductor?
A material with zero resistance at very low temperatures.
62. What is an electric circuit?
A closed path for electric current to flow.
63. What are the components of a circuit?
It includes a source, conductor, switch, and load.
64. What is a series circuit?
Components are connected end-to-end in one path.
65. What is a parallel circuit?
Components are connected across multiple paths.
66. What is the total resistance in a series circuit?
R_total
67. What is the total resistance in a parallel circuit?
1/R_total
68. What is the current in a series circuit?
The same current flows through all components.
69. What is the voltage in a series circuit?
Voltage divides across components (V
70. What is the current in a parallel circuit?
Current divides among branches (I
71. What is the voltage in a parallel circuit?
The same voltage is across all branches.
72. What is the total resistance of two 4 Ω resistors in series?
73. What is the total resistance of two 4 Ω resistors in parallel?
74. What happens if one bulb fails in a series circuit?
The circuit breaks, stopping all current flow.
75. What happens if one bulb fails in a parallel circuit?
Other bulbs continue to work independently.
76. What is a switch in a circuit?
A device to open or close the circuit.
77. What is a short circuit?
A low-resistance path causing excessive current flow.
78. What is an open circuit?
A break in the circuit stopping current flow.
79. What is a circuit diagram?
A symbolic representation of an electric circuit.
80. What is the symbol for a battery?
A long line (positive) and short line (negative).
81. What is the symbol for a resistor?
A rectangle represents a resistor in diagrams.
82. What is the symbol for an ammeter?
A circle with an “A” inside denotes an ammeter.
83. What is the symbol for a voltmeter?
A circle with a “V” inside denotes a voltmeter.
84. What is the advantage of a parallel circuit?
Components work independently, enhancing reliability.
85. What is the disadvantage of a series circuit?
A single failure stops the entire circuit.
86. What is electric power?
The rate at which electrical energy is consumed (P
87. What is the SI unit of power?
The SI unit is watt (W).
88. What is 1 watt?
1 W is 1 joule of energy per second.
89. What is the formula for power using resistance?
P
90. What is the power if V
91. What is the power if I
92. What is the power if V
93. What is electrical energy?
Energy transferred by electric current over time.
94. What is the formula for electrical energy?
Energy (E)
95. What is the SI unit of electrical energy?
The SI unit is joule (J).
96. What is 1 joule?
1 J is 1 watt of power for 1 second.
97. What is the commercial unit of electrical energy?
It is the kilowatt-hour (kWh).
98. What is 1 kilowatt-hour?
1 kWh is 3.6 × 10⁶ joules of energy.
99. How many joules are in 1 kWh?
1 kWh
100. What is the energy if P
E
101. What is the power of a 60 W bulb in 5 hours?
Energy
102. What is the cost if 1 kWh is ₹5 and 2 kWh is used?
Cost
103. What is a watt-hour?
Energy used by 1 watt for 1 hour (3600 J).
104. What is the power of a device using 240 J in 2 s?
105. What is the energy if V
106. What is the heating effect of current?
Electric current produces heat in a conductor.
107. What is Joule’s Law of heating?
Heat (H)
108. What is the unit of heat energy?
It is joule (J) in the SI system.
109. What causes heat in a conductor?
Collisions of electrons with atoms generate heat.
110. What is the heat if I
H
111. What is the heat if V
112. What is the heat if V
113. What is the practical use of the heating effect?
It’s used in electric heaters and toasters.
114. What is a fuse?
A safety device melting at high current to break the circuit.
115. What is the material of a fuse wire?
It’s made of a low-melting-point alloy like tin-lead.
116. What is the purpose of a fuse?
It prevents damage from excessive current flow.
117. What is an electric bulb’s filament?
A thin tungsten wire that glows when heated.
118. Why does a bulb glow?
The filament heats up and emits light due to current.
119. What is the resistance of a filament bulb?
It increases with temperature, making it non-ohmic.
120. What is an electric heater?
A device using high-resistance wire to produce heat.
121. What is the power rating of a heater?
It indicates the heat output, e.g., 1000 W.
122. What is the heat energy of a 2 kW heater in 1 h?
123. What is the advantage of the heating effect?
It enables cooking and warming appliances.
124. What is the disadvantage of the heating effect?
It causes energy loss in unwanted heat.
125. What is the heat loss in a 5 Ω wire with 3 A for 2 s?
126. What is domestic electric wiring?
A system distributing electricity in homes.
127. What is the standard voltage in India?
It is 220-240 V at 50 Hz AC.
128. What is a live wire?
A wire carrying current at high voltage.
129. What is a neutral wire?
A wire completing the circuit at zero voltage.
130. What is an earth wire?
A safety wire grounding excess current.
131. What is the color of a live wire in India?
It is red or brown.
132. What is the color of a neutral wire in India?
It is black or blue.
133. What is the color of an earth wire in India?
It is green or yellow-green.
134. What is earthing?
Connecting appliances to the ground for safety.
135. What is overloading?
Excessive current drawn beyond the circuit’s capacity.
136. What causes a short circuit?
Direct contact between live and neutral wires.
137. What is a circuit breaker?
A device automatically cutting off current during faults.
138. What is an MCB?
Miniature Circuit Breaker trips during overloads.
139. What is the advantage of an MCB over a fuse?
It can be reset, unlike a fuse that melts.
140. What is the role of a switch in wiring?
It controls the flow of current in a circuit.
141. What is the power rating of appliances?
It shows voltage and power usage, e.g., 220 V, 100 W.
142. What is the current in a 220 V, 1100 W heater?
143. What is an electric shock?
A sudden flow of current through the body.
144. What prevents electric shock?
Earthing and insulation prevent shocks.
145. What is the safe current through the human body?
Less than 1 mA is generally safe.
146. What is a galvanometer?
A device detecting small currents in a circuit.
147. What is a rheostat?
A variable resistor controlling current flow.
148. What is the use of a rheostat?
It adjusts resistance to regulate current or voltage.
149. What is a potentiometer?
A device measuring potential difference precisely.
150. What is the resistivity of a good insulator?
It is very high, e.g., 10¹² Ω·m for rubber.
151. What is the resistivity of a superconductor?
It is zero at critical temperatures.
152. What is the resistance of a 2 m wire with ρ
153. What is the total resistance of three 6 Ω resistors in series?
154. What is the total resistance of three 6 Ω resistors in parallel?
155. What is the current if three 2 Ω resistors in series have 12 V?
156. What is the voltage drop across a 3 Ω resistor with 2 A?
157. What is the power dissipated in a 5 Ω resistor with 4 A?
158. What is the energy in a 100 W bulb for 30 minutes?
159. What is the heat in a 10 Ω resistor with 2 A for 20 s?
160. What is the advantage of AC over DC?
AC can be transmitted over long distances efficiently.
161. What is the frequency of AC in India?
It is 50 Hz, reversing 50 times per second.
162. What is a step-up transformer?
It increases voltage for transmission.
163. What is a step-down transformer?
It decreases voltage for safe use.
164. What is the voltage drop in a parallel circuit?
It remains the same across all branches.
165. What is the current division in a parallel circuit?
Current splits inversely proportional to resistance.
166. What is the resistance if ρ
167. What is the current in a 12 V battery with 3 Ω total resistance?
168. What is the power of a 220 V, 5 A appliance?
169. What is the energy of a 500 W device in 2 hours?
170. What is the cost of 3 kWh at ₹4 per unit?
171. What is the heat in a 4 Ω resistor with 3 A for 10 s?
172. What is the voltage if P
173. What is the resistance if P
174. What is the current if P
175. What is the total resistance of 2 Ω and 3 Ω in series?
176. What is the total resistance of 2 Ω and 3 Ω in parallel?
177. What is the voltage across a 6 Ω resistor in series with 12 V?
If total R
178. What is the current in a parallel branch with 4 Ω and 12 V?
179. What is the energy of a 2 kW appliance in 30 minutes?
180. What is the power if E
181. What is the resistance if ρ
182. What is the voltage if Q
183. What is the current if Q
184. What is the heat in a 2 Ω resistor with 5 V for 10 s?
185. What is the total resistance of 5 Ω, 10 Ω in series?
186. What is the internal resistance of a battery?
Resistance within the battery reducing terminal voltage.
187. What is the formula for terminal voltage?
188. What is the terminal voltage if EMF
189. What is Kirchhoff’s First Law?
The sum of currents entering a junction equals those leaving.
190. What is Kirchhoff’s Second Law?
The sum of voltage drops equals the supplied voltage in a loop.
191. What is a Wheatstone bridge?
A circuit to measure unknown resistance accurately.
192. What is the condition for a balanced Wheatstone bridge?
R₁/R₂
193. What is a meter bridge?
A device using a wire to measure resistance.
194. What is the resistivity of silver?
It is about 1.59 × 10⁻⁸ Ω·m, lowest among metals.
195. What is the effect of doubling wire length?
Resistance doubles if area remains constant.
196. What is the effect of doubling wire area?
Resistance halves if length remains constant.
197. What is the resistance of a wire if doubled in length and area?
Resistance remains the same (L doubles, A doubles).
198. What is the power loss in transmission lines?
199. Why is high voltage used in transmission?
It reduces current, minimizing power loss (P
200. What is the resistance of a human body?
It varies, typically 1000 Ω when dry.
201. What is the danger of high current?
It can cause burns or stop the heart.
202. What is the resistance of a wet human body?
It drops to about 100 Ω, increasing shock risk.
203. What is the total current in two parallel branches of 2 A each?
I_total
204. What is the voltage across a 4 Ω resistor in parallel with 12 V?
Voltage remains 12 V across all branches.
205. What is the energy of a 1 kW device in 15 minutes?
206. What is the heat in a 6 Ω resistor with 4 V for 5 s?
207. What is the current in a 24 V circuit with 8 Ω resistance?
208. What is the power of a 110 V, 2 A fan?
209. What is the resistance if P
210. What is the total resistance of 3 Ω, 6 Ω in parallel?
211. What is the voltage if E
212. What is the current if E
213. What is the heat in a 3 Ω resistor with 6 V for 10 s?
214. What is the energy cost of 5 kWh at ₹6 per unit?
215. What is the power if a 220 V device uses 0.5 A?
216. What is the resistance of a 100 W, 220 V bulb?
217. What is the current in a 60 W, 220 V bulb?
218. What is the total resistance of four 8 Ω resistors in series?
219. What is the total resistance of four 8 Ω resistors in parallel?
220. What is the heat in a 1 Ω resistor with 10 V for 2 s?
221. What is the energy of a 250 W TV in 4 hours?
222. What is the power if E
223. What is the resistance if ρ
224. What is the voltage if P
225. What is the current if P
226. What is the energy of a 1.5 kW iron in 20 minutes?
227. What is the total resistance of 2 Ω, 4 Ω, 6 Ω in series?
228. What is the total resistance of 2 Ω, 4 Ω, 6 Ω in parallel?
229. What is the current in a 9 V circuit with 3 Ω resistance?
230. What is the heat in a 2 Ω resistor with 8 V for 5 s?
231. What is the power of a 12 V, 3 A motor?
232. What is the resistance if P
233. What is the energy cost of 10 kWh at ₹3 per unit?
234. What is the current in a 100 W, 50 V device?
235. What is the total resistance of 5 Ω and 10 Ω in parallel?
236. What is the heat in a 4 Ω resistor with 6 A for 3 s?
237. What is the power if E
238. What is the voltage if Q
239. What is the current if Q
240. What is the energy of a 400 W fan in 1 hour?
241. What is the resistance if ρ
242. What is the power if V
243. What is the current if P
244. What is the total resistance of 1 Ω, 2 Ω, 3 Ω in series?
245. What is the total resistance of 1 Ω, 2 Ω, 3 Ω in parallel?
246. What is the heat in a 5 Ω resistor with 10 V for 4 s?
247. What is the energy of a 3 kW device in 10 minutes?
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