Physics MCQs

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Myopia (short-sightedness) occurs when images are focused in front of the retina, causing distant objects to appear blurry. It is commonly due to an elongated eyeball or excessive corneal curvature. This defect is corrected using concave (diverging) lenses. Hyperopia, by contrast, focuses images behind the retina.

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Astigmatism is due to imperfect spherical nature of eye lens. The focal length of eye lens is in two orthogonal directions become different so they cannot see objects in two orthogonal directions simultaneously. This defect in direction can be removed by using cylindrical lens in a particular direction.

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The weight of a person would be maximum at the poles, due to the higher gravitational force acting upon them in these regions. This occurs because Earth is an oblate spheroid, flattened at its poles and bulging at the equator, resulting in a shorter distance from the Earth’s center at the poles and a consequent higher gravitational pull. At the equator, the force is slightly weaker due to a greater distance from the Earth’s center. Weights at the Tropics of Cancer and Capricorn lie in-between the poles and equator, but are closer to the equator’s value.

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The north pole of a magnet in a compass points north because it is attracted to the Earth’s magnetic south pole, which is located near Earth’s geographic north pole. The geographic north pole of earth corresponds to magnetic south pole and geographic south pole of earth corresponds to magnetic north pole. The direction in which a compass needle points is known as magnetic north. This is not exactly the direction of the North Magnetic Pole. Instead, the compass aligns itself to the local geomagnetic field, which varies in a complex manner over the Earth’s surface. The angular difference between magnetic north and true north (defined in reference to the Geographic North Pole), at any particular location on the Earth’s surface, is called the magnetic declination. Most map coordinate systems are based on true north, and magnetic declination is often shown on map legends so that the direction of true north can be determined from north as indicated by a compass.

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The solution involves converting the speed of the bus from km/hr to m/sec. This conversion is achieved by the formula speed (m/sec) = speed (km/hr) * 5/18. Thus, the speed becomes 20 m/s. The distance travelled by the bus in 5 seconds is the product of speed and time which gives us 100 meters. Therefore, option [D] or option 4 is the correct answer.

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During the storm, the velocity of wind above the roof surface is very high and hence pressure is low. The pressure below the roof is atmospheric which is higher than the pressure of upper surface. Due to this pressure difference, the roof blows.

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The velocity of an object undergoing uniform circular motion is always changing (because the direction is always changing). Further, since the acceleration is centripetal, it must always point toward the center of the circle; so, as the object moves around the circle, the acceleration vector is also constantly changing direction. Notice that for an object in uniform circular motion, both the velocity and the acceleration are changing because the directions of these vectors are always changing, even though their magnitudes stay the same. In this question, only speed remains unchanged.

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Electron microscope works on the principle of Wave Nature of electrons. Electron microscopes use an electron beam instead of visible light and an electron detector instead of our eyes. An electron beam allows us to see at very small scales because electrons can also behave as light due to its wave nature.

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Edwin Hubble, an american astronomer, and was the first to prove that the universe is expanding. According to Expanding Universe theory, the universe is presently expanding. Hubble proved that there is a direct relationship between the speeds of distant galaxies and their distances from Earth. This is now known as Hubble’s Law.

Notes:
The SI unit of Linear Momentum is kg m/s Linear Momentum = Mass(kg) x Velocity (m/s) Linear Momentum is the quantity of motion of a moving body. Dimensional Formula of Linear Momentum is [M¹ L¹ T^-1]