Tag: science & technology

Kalpana Chawla is correctly identified as the first Indian woman in space. She flew on Space Shuttle Columbia mission STS-87 in 1997 as a mission specialist. Although she was a US citizen born in India, she is recognized as the first woman of Indian origin in space. Sunita Williams later became the second Indian-American woman in space.

Saturn is correctly identified as the second biggest planet in our solar system. Jupiter is the largest, followed by Saturn at approximately 95 times Earth's mass. Saturn is famous for its prominent ring system and is a gas giant composed mostly of hydrogen and helium, making it the second-largest by both mass and volume.

False is correct - no human beings have ever set foot on Mars. All Mars exploration so far has been through robotic missions like rovers and landers. The Apollo missions (1969-1972) only landed humans on the Moon. Crewed Mars missions remain a future goal for space agencies like NASA and private companies like SpaceX.

Ohms is correctly identified as the unit of electrical resistance, named after Georg Ohm who formulated Ohm's Law (V=IR). Newton measures force, Mhos (now called Siemens) measures conductance (the inverse of resistance), and Cadila is not a physical unit. Resistance is fundamental to electrical circuits and determines how much a material opposes current flow.

A magnifying glass uses a convex lens, which is thicker in the middle than at the edges. This shape causes light rays to converge (bend inward), creating a magnified virtual image. Concave lenses are thinner in the middle and diverge light, making objects appear smaller.

A solar eclipse occurs when the moon passes directly between the sun and earth, blocking sunlight from reaching earth. The moon's shadow falls on earth's surface, temporarily darkening the sky. In a lunar eclipse, earth is between the sun and moon.

Sound is produced by the vibration of air molecules or any medium. These vibrations create pressure waves that our ears detect as sound. 'Photons of sound' is incorrect - photons are particles of light, not sound. Loudness is measured in decibels, not bels, making option C inaccurate.

Wavelength is defined as the distance between two consecutive crests or troughs of a wave. It represents the spatial period of the wave. Loudness is related to amplitude, frequency is the number of wave cycles per second, and amplitude is the maximum displacement from equilibrium.

Frequency is measured in both hertz and cycles per second - these are equivalent units. One hertz equals one cycle per second. This is a case where both naming conventions are valid and used interchangeably in physics.

Normal conversation typically measures around 60 decibels. 100 dB would be extremely loud (like a chainsaw or motorcycle), 50 dB is quieter than normal speech, and 80 dB is closer to heavy traffic or a noisy restaurant. The 60 dB range accurately represents typical human conversation levels.