Scientific Instruments — Set 4
Physics · वैज्ञानिक उपकरण · Questions 31–40 of 70
Which device is used to measure the potential difference between two points?
Correct Answer: D. Voltmeter
A voltmeter is an instrument used for measuring electrical potential difference in volts. It is always connected in parallel to the circuit component being measured. Ideal voltmeters have infinite resistance to avoid affecting the circuit current.
Which instrument is used to measure the strength of magnetic fields?
Correct Answer: A. Magnetometer
A magnetometer is a scientific instrument used to measure the strength and direction of magnetic fields. It is used in geophysical surveys to find mineral deposits or buried structures. Spacecraft also carry them to study the magnetic environments of other planets.
What is the function of a 'Dictaphone'?
Correct Answer: A. Recording and reproducing speech
The correct answer is 'Recording and reproducing speech'. A dictaphone is a device used to record spoken words that can later be played back and transcribed. It was historically used in business and legal settings before digital voice recorders became common. The term was originally a trademark but became a generic name for voice recorders.
Which instrument is used to measure the amount of rainfall?
Correct Answer: C. Rain Gauge
A rain gauge is a meteorological instrument used to gather and measure the amount of liquid precipitation. It usually consists of a cylinder with a graduated scale to show rainfall in millimeters. Accurate data from rain gauges is essential for agriculture and flood management.
Which instrument is used for examining very small objects?
Correct Answer: B. Microscope
A microscope uses lenses or electrons to magnify objects that are too small to be seen by the naked eye. Optical microscopes are common in schools, while electron microscopes are used for atomic-level research. This invention laid the foundation for modern microbiology and cell biology.
Which device is used to convert electrical energy into sound energy?
Correct Answer: C. Loudspeaker
A loudspeaker is a transducer that converts electrical audio signals into sound waves. It uses a coil and magnet to vibrate a diaphragm, creating pressure waves in the air. This technology is used in everything from mobile phones to concert sound systems.
Which instrument is used to measure the rate of flow of a liquid?
Correct Answer: D. Venturimeter
A venturimeter measures the flow rate of fluids in a pipe based on the Bernoulli principle. It creates a pressure difference by narrowing the pipe, which is then measured to calculate velocity. It is widely used in water distribution and chemical processing industries.
Which instrument is used to measure the intensity of light?
Correct Answer: A. Photometer
A photometer measures the strength of electromagnetic radiation in the range from ultraviolet to infrared. In photography, it is used as a light meter to determine the correct exposure settings. It compares the intensity of a light source with a standard source.
What is the purpose of a 'Stethoscope'?
Correct Answer: C. To hear sounds produced within the body
A stethoscope is an acoustic medical device for listening to internal sounds of the heart or lungs. It helps doctors detect abnormalities like heart murmurs or respiratory congestion. René Laennec invented the first version of this instrument in 1816.
Which instrument is used to measure the resistance of an electric circuit?
Correct Answer: A. Ohmmeter
An ohmmeter is an electrical instrument that measures the opposition to current flow in a component. It passes a small current through the component to calculate resistance based on Ohm's Law. Most modern multimeters include a built-in ohmmeter function.