Polytechnic Physics Set 1

1. One ohm is equal to

1 Volt 1 Ampere 1 Volt × 1 Ampere 1 Volt × (1 Ampere)²

Answer: 1 Volt × 1 Ampere

2. The SI unit of resistivity is

Ohm meter Per ohm per meter Ohm Ohm per meter

Answer: Ohm per meter

3. Calculate the number of electrons in a 1 Coulomb charge.

6.23 × 10¹⁰ electrons 6.23 × 10¹⁸ electrons 1.6 × 10¹⁰ electrons 1.6 × 10¹⁸ electrons

Answer: 6.23 × 10¹⁸ electrons

4. Electric power is equal to 1 Watt

1W = 1V × 1A 1W = 1V / 1A 1W = 1A / 1V 1W = 1V² × 1A

Answer: 1W = 1V × 1A

5. Heating appliances like bread toasters and electric irons are made of alloys rather than pure metals because

Alloys have lower resistivity Alloys have higher resistivity It does not depend on resistivity None of these

Answer: Alloys have higher resistivity

6. A ray passing parallel to the principal axis will go through

Principal focus Principal axis Radius of curvature Center of curvature

Answer: Center of curvature

7. When two devices are connected in parallel between two points A and B, the physical quantity that remains the same between the two points is

Current Voltage Resistance None of these

Answer: Voltage

8. The phenomenon of light diffraction by colloidal particles is called

Thermal effect Baldwin effect Raman effect Tyndall effect

Answer: Tyndall effect

9. An object of height 5 cm is placed at a distance of 20 cm from a convex mirror with a curvature radius of 30 cm. What is the height of the image?

0.428 cm 2.14 cm 1.1 cm 31.5 cm

Answer: 2.14 cm

10. The magnification produced by rear-view mirrors in vehicles is

Less than one More than one Equal to one Can be less or more, depending on the position of the object in front

Answer: Less than one

11. The type of mirror used by dentists to view enlarged images of patients’ teeth is

Concave Convex Plane Spherical

Answer: Concave

12. A student conducts an experiment using a convex lens. He places an object at a distance of 60 cm from the lens and finds that the image is formed at a distance of 30 cm behind the lens. What is the power of the lens?

0.005 D 0.05 D 5 D 50 D

Answer: 5 D

13. Why does a swimming pool appear less deep than it actually is?

Reflection of light Refraction of light Dispersion of light Total internal reflection

Answer: Refraction of light

14. When white light is dispersed through a prism, which color is refracted the most?

Violet Red Yellow Orange

Answer: Violet

15. 14 J of work is done to move a charge of 2 C between two points in a conductor. What is the potential difference between the two points?

28 V 14 V 7 V 3.5 V

Answer: 7 V

16. A spherical mirror and a thin spherical lens have a focal length of -15 cm. What is the nature of the mirror and lens?

Both are concave Both are convex The mirror is concave and the lens is convex The mirror is convex and the lens is concave

Answer: Both are concave

17. An object is placed 10 cm away from a convex mirror with a focal length of 15 cm. What is the magnification?

1.667 0.6 10 1.5

Answer: 0.6

18. If n resistors of resistance R are connected in parallel, what is their equivalent resistance?

R/n n²/R R/n² n/R

Answer: R/n

19. An electron enters a magnetic field perpendicularly, as shown in the figure. What will be the direction of the force acting on the electron?

To the right To the left Out of the paper’s surface Into the paper’s surface

Answer: To the left

20. The phenomenon of electromagnetic induction is

The process of moving a body The process of generating a magnetic field due to electric current passing through a coil The generation of induced electric current in a coil due to relative motion between a magnet and the coil The process of rotating a coil in an electric motor

Answer: The generation of induced electric current in a coil due to relative motion between a magnet and the coil