First month exam in physics

In the opposite circuit, the resistance (R) equals

• 610 ohm

• 630 ohm

• 650 ohm

• 670 ohm

In the opposite circuit, the ratio V1:V2=6 so (R) equals

• 10 ohm

• 4 ohm

• 6 ohm

• 12 ohm

In the circuit shown, the equivalent resistance between (A) and (B) equals

• 8 ohm

• 6 ohm

• 5 ohm

• 2 ohm

You are measuring the current through a conductor that is connected to a battery of 18V. The ammeter reads 40mA. Later you notice the current through the conductor has dropped to 20mA. How much has the voltage changed?

• 0 V

• 900 mV

• 9 V

• 18 V

In the opposite figure two conductors of same material and same cross-sectional area. When the switch (K) only is closed, the reading of the ammeter was (i1) and when the switch (L) only is closed, the reading of the ammeter was (i2), so the ratio i1:i2 equals

• 1:4

• 1:3

• 2:3

• 1

In the opposite figure, several identical resistances each of resistance (R) so total resistance between (A,B) is

• 7/6 R

• R

• 3/5 R

• 2/9 R

A conductor carrying current as in the figure, so total electric charge passes through it in 12sec equals

• 120 C

• 60 C

• 80 C

• 0

A wire of length 120cm, its resistance per unit length 8 ohm/meter, divided into 3 equal parts and one of them is shaped as a ring then connected with the rest parts. The equivalent resistance between its terminals (A) and (B) is

• 8 ohm

• 6.8 ohm

• 9.6 ohm

• 7.2 ohm

An aluminum cable of radius 9mm and resistance 5 ohm is replaced by another cable of 6 thin aluminum wires each of radius 3mm and of same length, so the resistance of the second cable is

• 3 ohm

• 18 ohm

• 15 ohm

• 7.5 ohm

A student made a resistor from a wire of certain length then made another resistor from another wire of same material but its diameter equals the radius of the first and its length equals double that of the first wire, so the resistance of the first wire to the resistance of the second wire R1:R2

• 1/8

• 8/1

• 4/1

• 1/4