Q: Which device is used to detect the direction of magnetic north?
Answer: Compass
Explanation: A magnetic compass uses a magnetized needle that aligns itself with the Earth's magnetic field. It has been a primary tool for navigation for centuries, helping travelers find their way. The needle always points toward the magnetic north pole.
Q: Which instrument is used for measuring small electrical potential differences?
Answer: Potentiometer
Explanation: A potentiometer is used to measure electromotive force (EMF) by balancing it against a known potential difference. It is more accurate than a voltmeter because it does not draw any current from the source at the point of balance. It is also used as a variable resistor in electronic circuits.
Q: Which instrument is used for observing celestial bodies like stars and planets?
Answer: Telescope
Explanation: An astronomical telescope gathers light from distant celestial objects to create a magnified image. Galileo was one of the first to use this instrument to discover the moons of Jupiter. Modern telescopes can be ground-based or placed in space, like the Hubble telescope.
Q: Which instrument is used to measure the speed of an automobile?
Answer: Speedometer
Explanation: A speedometer shows the instantaneous speed of a vehicle in motion, usually in km/h or mph. It is mandatory in all motorized vehicles for safety and legal compliance. Most modern speedometers are electronic and use sensors on the transmission or wheels.
Q: What is the function of a 'Bolometer'?
Answer: Measuring heat radiation
Explanation: A bolometer is an instrument used for measuring the power of incident electromagnetic radiation via heating. It is extremely sensitive and can detect very small changes in temperature. It is widely used in infrared astronomy to detect distant heat sources.
Q: Which instrument is used to measure the pressure of blood in the arteries?
Answer: Sphygmomanometer
Explanation: A sphygmomanometer is the standard medical device used to check blood pressure. It consists of an inflatable cuff and a pressure-measuring unit, either mercury or digital. High blood pressure readings can indicate risks for cardiovascular diseases.
Q: Which instrument is used to measure the temperature of the human body?
Answer: Clinical Thermometer
Explanation: A clinical thermometer is specifically calibrated to measure body temperature, typically between 35 and 42 degrees Celsius. It often has a small constriction in the tube to prevent the mercury from falling back immediately. Digital versions have largely replaced mercury ones for safety reasons.
Q: Which device is used for measuring the intensity of light?
Answer: Photometer
Explanation: A photometer is used to measure light intensity and other optical properties of surfaces. It is used in photography to ensure the correct amount of light enters the camera. In science, it helps analyze chemical concentrations by measuring light absorption.
Q: Which instrument is used for detecting underwater objects using sound?
Answer: Sonar
Explanation: Sonar stands for Sound Navigation and Ranging and uses sound propagation to navigate or detect objects. It is the primary tool for mapping the seafloor and locating shipwrecks or schools of fish. Underwater, sound waves travel much further than light or radio waves.
Q: Which instrument is used to measure the moisture content in the atmosphere?
Answer: Hygrometer
Explanation: A hygrometer is the specific instrument used to measure atmospheric humidity. High humidity levels can affect weather patterns and human comfort. It is essential in places like libraries and museums to protect sensitive materials.