An ice block with a piece of lead embedded in it floats in water. If the ice melts the water level (1) Rises (2) Falls (3) Remains same (4) Falls first and then rises Answer: (2) If ρ1 is the density of the lead piece of volume v, the volume of water displaced by the ice … Read more
The velocity of heat radiation in a vacuum is (1) Equal to that of light (2) Less than that of light (3) Greater than that of light (4) Equal to that of sound Answer: (1) Electrons are generally responsible for heat conduction. The phonons (vibrations of the nuclei) also play a part, depending on the temperature … Read more
The plastic material commonly used for making gear wheels is (1) Polyesters (2) Nylons (3) Bakelit (4) Polystyrene Answer: (2) Popular materials for plastic gears are acetal resins such as DELRIN, Duracon M90; nylon resins such as ZYTEL, NYLATRON, MC901 and acetal copolymers such as CELCON. The physical and mechanical properties of these materials vary with … Read more
Ultraviolet radiations of the Sun do not reach the earth because the earth’s atmosphere is surrounded by (1) Carbon dioxide (2) Ammonia (3) Chlorine (4) Ozone Answer: (4) The ozone layer absorbs 97–99% of the Sun’s medium-frequency ultraviolet light (from about 200 nm to 315 nm wavelength), which potentially damages exposed life forms on Earth. Ozone … Read more
“Curie” is a unit of : (1) Radioactivity (2) Temperature (3) Heat (4) Energy Answer: (1) Curie, in physics, a unit of activity of a quantity of a radioactive substance, was named in honour of the French physicist Marie Curie. One curie (1 Ci) is equal to 3.7 × 1010 becquerel (Bq). Radioactivity refers to the … Read more
Which of the following is used in the oven? (1) X-rays (2) UV rays (3) Microwaves (4) Radiowaves Answer: (3) An oven that uses micro radiation waves as a source of heat to cook food as opposed to a fire source. Conceptualized in 1946, Dr Perry Spencer allegedly discovered the healing properties of microwaves while studying … Read more
When heated from 0C to 100C volume of a given mass of water will : (1) Increase gradually (2) Decrease gradually (3) Increase and then will decrease (4) Decrease and then will increase Answer: (4) When heated from 0C to 100 C volume of a given mass of water will first decrease and then increase. If … Read more
Energy is continuously created in the sun due to: (1) nuclear fusion (2) nuclear fission (3) radioactivity (4) artificial radioactivity Answer: (1) The central mass of the sun becomes increasingly hot and dense, eventually initiating thermonuclear fusion in its core. It is thought that almost all other stars form by this process. nuclear fusion is a … Read more
In electronics what comes under the tank circuit? (1) Resistance and capacity (2) Resistance and inductance (3) Capacity and inductance (4) Resistance, capacity and inductance Answer: (3) An LC circuit, also called a resonant circuit, tank circuit, or tuned circuit, consists of an inductor, represented by the letter L, and a capacitor, represented by the letter … Read more
Coolis tube is used to produce (1) Radio waves (2) Microwaves (3) X-rays (4) Gama rays Answer: (3) X-rays are part of the electromagnetic spectrum, ionizing radiation with wavelengths shorter than ultraviolet light. X-ray tubes evolved from experimental Crookes tubes with which X-rays were first discovered in the late 19th century, and the availability of this … Read more