Model Test Paper മാതൃകാ ചോദ്യപേപ്പർ
A full paper in the Kerala Class 9 Physics pattern for this chapter, covering the whole of “Current Electricity” – charge and current, potential difference and emf, cells and their combinations, circuit symbols and meters, Ohm’s law, the factors that affect resistance, the rheostat, series and parallel circuits, household wiring and the LED resistor. Several questions have circuit diagrams drawn with the symbols of Table 7.5. Work on paper with a timer before you look at the solutions.
Standard IX · Physics
Chapter 7 · ധാരാവൈദ്യുതി · Current Electricity
- The first 15 minutes are cool-off time: read every question and plan your answers; do not write.
- Answer all questions. Marks for each question are shown on the right.
- For numericals write Given → Formula → Substitution → Answer with the unit. Convert mA to A before substituting.
- Draw circuit diagrams with the standard symbols; in a cell the long line is the + terminal. Meters are ideal.
SECTION AAnswer all · 8 × 1 = 8 marks
1.
The SI unit of electric charge is .
(1)2.
Which of the following changes light energy into electrical energy?
(1)(a) dry cell(b) dynamo(c) solar cell(d) car battery
3.
The potential difference between the terminals of a cell when no current is drawn from it is called its .
(1)4.
Find the relation and fill in: potential difference : volt :: electric current :
(1)5.
Three identical 1.5 V cells are connected in parallel (+ to +, − to −). The potential difference they give is
(1)(a) 0.5 V(b) 1.5 V(c) 3 V(d) 4.5 V
6.
Name the component whose circuit symbol is shown in the figure.
(1)7.
An electric current in a metal wire is a flow of
(1)(a) protons(b) free electrons(c) positive ions(d) whole atoms
8.
The length of a wire is doubled, while its material and thickness stay the same. Its resistance
(1)(a) becomes half(b) stays the same(c) doubles(d) becomes four times
SECTION BAnswer all · 5 × 2 = 10 marks
9.
12 C of charge flows through a bulb in 4 s. (a) Find the current through the bulb. (b) How much charge flows through it in one minute?
(2)10.
24 J of work is done in moving 4 C of charge from a point A to a point B of a circuit. (a) Find the potential difference between A and B. (b) How much work is needed to move 10 C of charge between the same two points?
(2)11.
Draw the circuit diagram of a circuit with a cell, a switch, a bulb, an ammeter to measure the current through the bulb and a voltmeter to measure the potential difference across the bulb. Mark the + and − terminals of both meters.
(2)12.
The figure shows two 1.5 V cells joined in three ways, (a), (b) and (c), each with a voltmeter. Write the reading of the voltmeter in each case. Which arrangement must never be used?
(2)13.
A fan and its regulator are connected in series, but the fan and the light of a room are connected in parallel. Give a reason for each.
(2)SECTION CAnswer all · 4 × 3 = 12 marks
14.
The table shows the readings of an experiment with a resistor, at constant temperature.
(a) Find the resistance of the resistor. (b) Find the missing current. (c) State Ohm’s law.
(3)| Potential difference V (volt) | 1.5 | 3.0 | 4.5 | 6.0 |
|---|---|---|---|---|
| Current I (ampere) | 0.25 | 0.50 | 0.75 | ? |
15.
A 5 Ω and a 10 Ω resistor are connected in series with a 4.5 V battery and a switch (figure). (a) Find the effective resistance. (b) Find the current in the circuit. (c) Find the potential difference across each resistor.
(3)16.
A 6 Ω and a 12 Ω resistor are connected in parallel to a 6 V battery, with an ammeter in the main wire (figure). (a) Find the effective resistance. (b) Find the current through each resistor. (c) What does the ammeter read?
(3)17.
An LED works at 2 V with a current of 20 mA. It is to be lit with a 9 V battery. (a) What potential difference must a resistor in series with it take? (b) Find the resistance needed. (c) What would happen if the LED were connected to the battery without the resistor?
(3)SECTION DAnswer all · 2 × 5 = 10 marks
18.
A uniform nichrome wire 1 m long has a resistance of 8 Ω. (a) What is the resistance of a 50 cm piece of this wire? (b) Another nichrome wire is also 1 m long but has double the area of cross-section. What is its resistance? (c) The 1 m wire (8 Ω) is stretched evenly to 2 m. Find its new resistance. (d) Why is nichrome, and not copper, used for the heating coil of an iron box? (e) How does a rheostat change the current in a circuit?
(5)19.
In the circuit in the figure, a 2 Ω resistor (R1) is in series with a parallel combination of 6 Ω (R2) and 3 Ω (R3). The battery gives 3 V. (a) Find the effective resistance of the parallel part. (b) Find the total resistance of the circuit. (c) What does the ammeter read? (d) What does the voltmeter read? (e) Find the current through R2 and through R3.
(5)