Scientific Instruments — Set 3

Correct Answer: D. Screw Gauge

A screw gauge, also known as a micrometer, is used to measure the diameter of thin wires or thickness of sheets. It works on the principle of the 'pitch' of a screw thread. It offers much higher precision than a standard vernier caliper.

Correct Answer: A. Rotation speed

A tachometer measures the rotation speed of a shaft or disk, such as in a motor or engine. It usually displays the revolutions per minute (RPM) on a calibrated analog or digital dial. Vehicle dashboards often feature a tachometer next to the speedometer.

Correct Answer: B. Wattmeter

A wattmeter measures the electrical active power in watts of any given circuit. It combines the functions of an ammeter and a voltmeter to calculate energy flow. This is essential for monitoring energy consumption in industrial and domestic settings.

Correct Answer: C. Electroscope

An electroscope is a scientific instrument used to detect the presence and magnitude of electric charge. The gold-leaf electroscope is a classic example where leaves diverge when charged. It was one of the earliest tools used in the study of electricity.

Correct Answer: A. Detecting and locating distant objects

Radar stands for Radio Detection and Ranging and uses radio waves to determine the position of objects. It can calculate the distance, speed, and direction of aircraft, ships, or weather formations. It is a critical technology for modern air traffic control and defense.

Correct Answer: B. Salinometer

A salinometer measures the concentration of salt in a solution, typically seawater. It often works by measuring the electrical conductivity of the water, which increases with salt content. This is important for oceanography and maintaining industrial boilers.

Correct Answer: C. Transistor

A transistor is a semiconductor device used to amplify or switch electronic signals and power. It is the fundamental building block of modern electronic devices like computers and phones. Invention of the transistor revolutionized the field of electronics in the 20th century.

Correct Answer: C. Calorimeter

A calorimeter is an insulated container used to measure the amount of heat involved in a physical or chemical process. It helps scientists determine the energy content of food or fuels. The process of using this device is known as calorimetry.

Correct Answer: D. Distance traveled

An odometer records the total distance traveled by a vehicle since its manufacture. It is usually found on the dashboard and may be mechanical or digital. This information is vital for scheduling vehicle maintenance and determining resale value.

Correct Answer: C. Endoscope

An endoscope is a flexible tube with a camera that allows doctors to see inside hollow organs. It is used in procedures like colonoscopy or gastroscopy to diagnose internal health issues. This tool enables minimally invasive surgery and detailed internal examinations.