ECAT Pre Computer Science Chapter 12 MCQ Test With Answer

The powers of tow electric bulbs are 100 W and 200 W. Both of them are joined with 220 V mains. The ratio of resistances of their filaments will be

• 1 : 2 A
• 2 : 1 B
• 1 : 4 C
• 4 : 1 D

A conducting wire is drawn to double its length. Final resistivity of the material will be

• Double of the original one A
• Half of the original one B
• One fourth of the original one C
• Same as original one D

The energy stored in a charge capacitor

• 1/2CV² A
• 1/2C²V B
• 1/2C/V² C
• None of these D

Resistor is a device which convert electric energy to

• Heat energy A
• Chemical energy B
• Elastic energy C
• All of the above D

Solar cell converts sunlight directly into

• potential energy A
• thermal energy B
• mechanical energy C
• electrical energy D

The electric field due to an infinite long thin wire at a distance R varies as

• 1/R A
• 1/R² B
• R C
• R² D

Three resistors of resistance 2,3 and 6 ohms are connected in parallel, their equivalent resistance is

• 11.0 ohm A
• 1.0 ohm B
• 7.0 ohm C
• 3.0 ohm D

A car battery has e.m.f 12 volt and internal resistance 5 x 10^-2ohm. If it draws 60 ampere current, the terminal voltage of the battery will be

• 5 volt A
• 3 volt B
• 15 volt C
• 9 volt D

If the distance between the plates of a parallel plate condenser of capacity 10μF is doubled then new capacity will be

• 5μF A
• 20μF B
• 10μF C
• 15μF D

• 5μF A
• 10μF B
• 3μF C
• 6μF D

In Pakistan electricity is supplied for domestic use at 220 V, it is supplied at 110 V in USA. If the resistance of a 60 W bulb for use in Pakistan is R, the resistance of a 60 W bulb for use in USA will be

• 2 R A
• R/4 B
• R/2 C
• R D

Physicist George Simon ohm was a

• German physical A
• French physicist B
• Chinese physicist C
• Russian physicist D

An electric charge at rest is

• Only an electric field A
• Only a magnetic field B
• Both electric and magnetic fields C
• None of the above D

Ohm is the unit of

• current A
• capacitance B
• energy C
• resistance D

Which one of the following has larger value of relative permitivity E_rat room temperature?

• Vaccum A
• Air B
• Glass C
• Water D