Current Electricity

A current of 16 mA flows through a conductor. The number of electrons flowing per second is

• 10¹⁴

• 10¹⁵

• 10^-17

• 10¹⁷

In an external circuit the direction of flow of conventional current is

• In the direction of flow of electrons

• From negative to positive

• From positive to negative

• None of these

The magnitude of the drift velocity is of the order of;

• 10^-3m/s

• 10^-4m/s

• 10^-6m/s

• 10³m/s

Two resistance R1 and R2 have effective resistance Rs when connected in series and Rp when connected in parallel. If Rs Rp=16 and  $R1/R2$    =4. Calculate the value of R1 and R2.

• R1=1, R2=0.25  

• R1=2, R2=0.5

• R1=4, R2=1

• R1=8, R2=2

Which of the following statements is not true

• Conductance is the reciprocal of resistance and is measured in Siemens.

• Ohm’s law is not applicable at very low and very high temperature

• Ohm’s law is applicable to semiconductors

• Ohm’s law is not applicable to electron tubes, discharge tubes and electrolysis

The resistance of a wire is R. It is stretched uniformly so that its length is tripled. The new resistance of the wire

• 3R

• R

• R/3

• 9R

If three resistances R₁, R₂ and R₃ are joined in parallel across some potential source, then

• Equivalent resistance< lowest individual resistance

• Applied potential difference = potential difference across each resistance

• Current supplied by the source is shared among three resistance inversely in their ratio

• All of the above

A wire of resistance R is cut into two equal parts, its resistance becomes R/2, what happens to resistivity;

• Double

• Same

• Half

• One fourth

The resistance of 2, 3, 4 are connected in parallel. Their equivalent resistance will be minimum if they are connected in;

• In series

• In parallel

• In series

• Any of above

Filament resistance in a 500 W, 200 V light bulb is;

• $80Ω$

• $50Ω$
  

• $2.5Ω$

• $0.4Ω$