Polytechnic Physics Set 9

161. The ability of the eye to focus on both near and distant objects while adjusting the focal length is called ________.

Minimum distance of clear vision Nearsightedness Eye accommodation Farsightedness

Answer: Eye accommodation

162. Two magnetic field lines

Intersect at the midpoint Intersect near the north pole Never intersect each other Intersect near the south pole

Answer: Never intersect each other

163. Devices with metallic bodies are generally connected to the ground wire. What is the reason for grounding these wires?

To prevent excess electricity To provide high resistance to the device To supply excess electricity to the device To prevent electrical leakage

Answer: To prevent excess electricity

164. An electromagnet is made of _____.

Soft iron Brass Aluminum None of the above

Answer: Soft iron

165. The breaking of light into its constituent colors is called _____.

Refraction of light Scattering of light Dispersion of light Atmospheric refraction

Answer: Dispersion of light

166. The center of the reflective surface of a spherical mirror is a point called _____.

Center of curvature Aperture Pole Principal focus

Answer: Center of curvature

167. The principal focus of a spherical mirror is located exactly between _____.

Radius of curvature and pole Pole and center of curvature Center of curvature and radius of curvature Object and radius of curvature

Answer: Pole and center of curvature

168. The type of mirror used in vehicle headlights is

Convex Plane Concave None of the above

Answer: Concave

169. According to the Cartesian coordinate system, all distances are measured with respect to the principal focus from _____.

Center of curvature Pole Radius of curvature Principal focus

Answer: Pole

170. The radius of curvature of a convex mirror used for the rearview mirror of an automobile is 3 m. If a bus is located 5 m away from this mirror, the image will be formed at a distance of _____.

1.5 m 0.15 m 1.4 m 1.15 m

Answer: 1.4 m

171. The magnification produced by a plane mirror is +1. This means

Object distance > Image distance Image distance > Object distance Object distance = Image distance Object distance is twice the image distance

Answer: Object distance = Image distance

172. In an electric circuit, a device called _____ is often used to change the resistance in the circuit.

Capacitor Current controller Inductor Battery

Answer: Current controller

173. What material is used for the filaments of electric bulbs?

Tungsten Iron Aluminum Ebonite

Answer: Tungsten

174. A voltmeter is used in an electric circuit to measure _____.

Potential difference Electric current Resistance None of the above

Answer: Potential difference

175. Name the type of lens used to correct myopia (nearsightedness).

Concave lens Convex lens Convex mirror None of the above

Answer: Concave lens

176. The phenomenon of light diffraction can be observed in _____.

The blue color of the sky The red appearance of the sun at sunrise The red appearance of the sun at sunset All of the above

Answer: All of the above

177. The crystalline lens becomes milky and cloudy in old age; this condition is called _____.

Hyperopia (farsightedness) Myopia (nearsightedness) Cataract Presbyopia

Answer: Cataract

178. The symbolic representation of a resistor with resistance R is

+—/\/\/\—+ +—◯◯◯◯◯—+ +—R—+ +—0—+

Answer: +—R—+

179. Which of the following is a good conductor of electricity?

Paper Rubber Glass Iron

Answer: Iron

180. The SI unit of electric current is

Volt Faraday Ampere Ohm

Answer: Ampere