Download Chapt-13-electric current

A rectangular block of iron has the dimensions 1.2cm x 1.2cm x 15 cm
What is the resistance of the opposing square ends?
What is the resistance between two of the rectangular faces? (The resistivity ‘p’ for iron at room
temperature is 9.6 x 10–8 Ω – m) (K. Board 2008)
2
A 50 ohm resistor is required from a copper wire, 0.2 mm in diameter. What is the length of the wire
needed?(p = 1.6 x 10–8 Ω-m) (K. Board 2006)
3
Two resistances of 10 ohms and 50 ohms are connected is series with a 6 volt battery.
Calculate The charge drawn from the battery per minute. The power dissipated in 10 ohm
resistance. (K. Board 2005)
Q-5. A 50 ohm resistor is to be wound with platinum wire, 0.1 mm in diameter. How much wire is
needed (p = 11 × 10–8 Ωm)?
(K. Board 2003)
Q-9. Find the equivalent resistance in the given circuit, current I and potential difference between a and
b:
(K. Board 2003)
R1
=
5Ω
R2
=
2Ω
R3
=
3Ω
R4
=
6Ω
V
=
6 volts
1
Q-13. The resistance of a tungsten wire used in the filament of a 60 watt bulb is 240 Ω when the bulb is
hot at a temperature of 2020oC, what would you estimate its resistance at 30oC? (The temperature
coefficient of tungsten α 0.0045/oC). (K. Board 2002)
Q-19. A battery of 24V is connected to a 10Ω load and current of 2.2 amp is drawn; find the internal
resistance of the battery and its terminal voltage.
(K. Board 2002)
Q-20. Find the equivalent resistance and the current through R3 & R4.
Given R1 = 20Ω,
(K. Board 2001)
R2 = 30Ω, R3 = 20Ω, R4 = 40Ω, R5 = 40Ω
Q-25. You are given three resistors each of 2 ohm. How would you arrange these resistors to obtain the
equivalent resistances of
i)
1.5 ohm
ii)
3 ohms
iii)
6 ohm?
Also prove the result mathematically.
(K. Board 2000)