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Syllabus
(a) copper (b) mercury (c) carbon (d) platinum.
rod is held close to the suspended table-tennis ball shown in Fig. 8.1. The table-tennis
ball is covered with metal paint and is initially uncharged.
positively
charged rod
light
table-tennis ball
covered with metal
paint
nylon thread
Fig. 8.1
(i) Describe what happens to the charges on the metal-painted table-tennis ball as the
positively-charged rod is brought close to the ball.
(a) the total resistance of the circuit, and
(b) the reading of ammeter A.
of electrons transferred. Which way these electrons move. Charge on an electron = 1.6 × 10–19 C.
25. A sound is produced at one end of a long steel rail. Two distinct sounds are observed on the other end of this rail. Why ? The time gap between these sounds is found to be 0.35 second. What is the length of the rail ? Speed of sound in air = 330 . Speed of sound in steel = 5100 .
[123.5 m]
Q.19. In a circuit given below, find:
(i) Total resistance of the circuit,
(ii) Total current flowing in the circuit, and
(iii) The potential difference across
Q. If a glass rod is rubbed with silk cloth, the glass rod acquires a positive charge of 12.8 C. Calculate number of electrons transferred. Which way these electrons move. Charge on electron = 1.6 x C.
Q. What current flows in a resistance of 2kohm when
(i) a p.d. of 9 V and
(ii) a p.d of 6 mV is applied one by one?
Q. What do you mean by electric potential. Explain it by taking the analogy to liquid flow and heat flow.
Q. A current of 5 mA flows through solution for 40s. How many Cu' ' ions will deposit on cathode of the apparatus?
Q. Two lamps one rated 40 wan at 220 volt and other 60 watt 800 volt are connected in parallel to the Electric Supply at 220 volt.
(a) Draw a circuit diagram to show the connections
(b) Calculate the current drawn from the Electric Supply
(c) Calculate the total energy consumed by the two lamps together when they operate for 1hour.
ANS . b(0.45A) C (356.4 K3)
Q). Why do we see the lightning in sky first and hear its thunder there after? A man starts a stop watch no sooner he sees the lighting in the clouds and stops the watch when he hears the thunder. If the time gap between the two events is 1.8 seconds find the height of the clouds. Velocity of sound = 340 .
[612 m]
Q). A 5 coulomb charge is moved from one conductor to other. It does 10 joules of work. What is the potential difference between the two conductors? [2 V]
Q. If 0.2 C charge passes through cross-section of a conductor is 200 s, calculate the current in the conductor.
Q.17. The figure shows two resistors of same material and same cross-section area but having lengths 2l and l respectively. What is the ratio of their resistances?
[Ans. 2 : 1]
a. increase
b. decrease
c. first decrease and then increase
d. remain unchanged
Please do not provide any link.
Q.8. Two wires of the same material and same length have radii 1 mm and 2 mm respectively. Compare :
(i) their resistances, (ii) their specific resistance.
Ans. (i) 4 : 1 (ii) 1 : 1
Q.12. A conductor carries 2 ampere current. Calculate the amount of charge flown through a cross-section of this conductor in 10 s. [20 C]
Q14. An electric motor runs at 25 A current. What is the amount of charge drawn from the battery connected to the motor in 30 s ?