There is a resistance to the flow of charges in all electric circuits. The circu

Question

There is a resistance to the flow of charges in all electric circuits. The circuit element 'resistor R is used to show the resistance to the current in the circuit. The value of the resistance is measurec in ohm denoted by Greek alphabet (). The simple expression that describes the relation between current and voltage is called Ohm's law, and is, V-IR where I for current, V for voltage and R for resistance of the resistor. Resistance of any material is described by resistivity (p). Depending on the size (length L and area A), the relation describing the resistance R is, R = , where called resistivity is a measure of electrical property of the material. The relation for electrical power P is as follows P=VI = 12R= la) If the diameter of the wire increases, then the resistance b) If the length of the wire decreases, then the resistance c) When a battery with a very low internal resistance is part of a complete circuit, the voltage across the terminals of the battery is very close to of the battery. It is called, terminal voltage emf power output potential energy d) Is Ohm's law applicable to all materials? Why or why not with examples? e) Two resistors A and B are connected to the electrodes of a battery. The current in resistor A is twice the current in resistor B. Are resistors in series? What is the resistance of B if A is 10 ohm? 0) Why is it important to know the maximum current and voltage of a resistor from its power rate?

Explanation / Answer

(A) R = rho L / A

diameter increase then A increases.

so R decreases .....Ans

(B) L decreases then R also decreases. ....Ans

(C) Ans: emf , terminal voltafe

(D) No not on all.

semiconductor materials does not follow ohm law.

(e) NO, if they were connected in series then current had to be equal.

RA iA = RB iB

(10) (2i) = (i) (RB)

RB = 20 ohm ....Ans

(f) because these are the limits.

if we connect them with more than maxiumum voltage rating or current is flowing greater than rating.

then device can damage and will not work properly.

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