1.
The Element of an electric heater is made of____
Correct Answer
A. Nichrome
Explanation
The element of an electric heater is made of nichrome. Nichrome is an alloy made of nickel and chromium, which has high electrical resistance and is able to withstand high temperatures. This makes it suitable for heating elements in electric heaters, as it can generate heat efficiently and safely. Copper and aluminum are not commonly used for heating elements in electric heaters due to their lower resistance and lower melting points. Therefore, the correct answer is nichrome.
2.
When water is heated from 0 degrees Celsius to 100 degrees Celsius, the volume of water__
Correct Answer
D. First decrease, then increase
Explanation
When water is heated from 0 degrees Celsius to 100 degrees Celsius, the volume of water first decreases and then increases. This is because water follows a specific pattern of behavior as it is heated. Initially, as the temperature rises, the water molecules gain energy and move faster, causing them to spread out and decrease in density. This leads to a decrease in volume. However, once the temperature reaches a certain point (around 4 degrees Celsius), the water molecules start to form a unique arrangement that allows them to occupy more space, causing the volume to increase. This behavior continues until the boiling point is reached at 100 degrees Celsius.
3.
At what temperature are the temperature in Celsius and Fahrenheit scales equal?
Correct Answer
C. – 40 degrees Celsius
Explanation
At -40 degrees Celsius, the temperature in Celsius and Fahrenheit scales are equal. This is because -40 degrees Celsius is equal to -40 degrees Fahrenheit. The Fahrenheit scale is based on the freezing and boiling points of water, while the Celsius scale is based on the freezing and boiling points of water at sea level. The two scales intersect at -40 degrees, making it the temperature at which they are equal.
4.
Galvanometer can be converted into a voltmeter by using __
Correct Answer
B. High resistance in series
Explanation
By connecting a high resistance in series with a galvanometer, the current passing through the galvanometer is reduced. This allows the galvanometer to measure higher voltages without getting damaged. The high resistance in series acts as a voltage divider, dividing the total voltage across the circuit between the galvanometer and the high resistance. This conversion allows the galvanometer to function as a voltmeter, which is used to measure voltage.
5.
Light from the laser is________
Correct Answer
A. Monochromatic
Explanation
Monochromatic light refers to light that consists of a single color or wavelength. In the context of the question, the laser emits light that is monochromatic, meaning it produces a single specific color or wavelength of light. This is a characteristic feature of laser light, which is highly focused and has a narrow wavelength range.
6.
Choke is used to______
Correct Answer
A. Reduce the current in AC circuit
Explanation
A choke is an inductor that is used to impede or limit the flow of alternating current (AC) in a circuit. It is designed to offer high impedance to AC while allowing DC to pass through with little resistance. By introducing a choke in an AC circuit, it effectively reduces the current flowing through the circuit, thereby controlling the flow of electricity.
7.
In a standing wave the distance between a node and adjacent antinode is______
Correct Answer
C. λ / 4
Explanation
In a standing wave, the distance between a node and an adjacent antinode is equal to one-fourth (λ/4) of the wavelength. This is because a standing wave is formed by the interference of two waves of the same frequency and amplitude, traveling in opposite directions. The nodes are points of complete destructive interference, where the two waves cancel each other out, while the antinodes are points of complete constructive interference, where the two waves reinforce each other. The distance between a node and an adjacent antinode is one-fourth of the wavelength because it represents half a wavelength from the node to the antinode, and the full wavelength is twice that distance.
8.
The weight of a body is______
Correct Answer
B. Maximum at the poles
Explanation
The weight of a body is maximum at the poles because the force of gravity is strongest at the poles due to the earth's shape. The earth is slightly flattened at the poles and bulges at the equator, causing a greater gravitational pull at the poles. Therefore, objects weigh more at the poles compared to other locations on the surface of the earth.
9.
In which among the following is alternating current NOT used?
Correct Answer
C. Electroplating
Explanation
Alternating current (AC) is not used in electroplating. Electroplating is a process that uses direct current (DC) to deposit a thin layer of metal onto an object. The object to be plated is made the cathode and the metal to be plated is made the anode. When direct current is passed through the electrolyte solution, metal ions from the anode are attracted to the cathode and get deposited onto it. Alternating current is not suitable for electroplating as it would cause the metal ions to continuously move back and forth, resulting in an uneven and poor quality plating.
10.
Which of the following principles explains why light bends when it passes from one medium to another?
Correct Answer
D. Snell's Law
Explanation
Snell's Law describes how light bends, or refracts, when it passes from one medium into another with a different refractive index. This bending occurs due to the change in the speed of light as it moves between media of different densities.
11.
Ohmic conductor among the following is _____
Correct Answer
D. Constantum
Explanation
Constantum is the correct answer because an ohmic conductor is a material that follows Ohm's law, which states that the current flowing through a conductor is directly proportional to the voltage across it. Constantum is a fictional material that is often used in physics problems to represent an ideal ohmic conductor. Transistors, thermal value, and electrolyte are not ohmic conductors.
12.
If a red-green flag is seen in green light it appears to be of which of the following colour?
Correct Answer
C. Black - Green
Explanation
When a red-green flag is seen in green light, it appears to be black-green in color. This is because the flag is primarily red in color, and when green light shines on it, the red color is absorbed and only the green color is reflected, resulting in a black-green appearance.
13.
A moving electric charge produces_______
Correct Answer
C. Both electric and magnetic field
Explanation
A moving electric charge produces both an electric field and a magnetic field. This is known as electromagnetic radiation. When an electric charge moves, it creates a disturbance in the surrounding electric field, which then generates a magnetic field perpendicular to the direction of the charge's motion. These two fields are interconnected and propagate as electromagnetic waves. This phenomenon is fundamental to the understanding of electricity and magnetism and is described by Maxwell's equations.
14.
Lightning conductors are made up of _____
Correct Answer
C. Copper
Explanation
Copper is used to make lightning conductors because it is an excellent conductor of electricity. It has low resistance, allowing the lightning current to flow easily through it and safely into the ground. Copper is also highly durable and resistant to corrosion, making it a reliable choice for outdoor applications. Additionally, copper has a high melting point, which is important in withstanding the intense heat generated by a lightning strike.
15.
Which among the following quantities is scalar?
Correct Answer
A. Speed
Explanation
Speed is a scalar quantity because it only requires magnitude and direction to be fully described. Scalar quantities do not have a specific direction associated with them, and speed can be described by its magnitude, not taking into account the direction in which an object is moving. On the other hand, acceleration, displacement, and force are vector quantities because they require both magnitude and direction to be fully described.
16.
Nichrome wire is used in an electric heater because_______
Correct Answer
D. All of the above
Explanation
Nichrome wire is used in an electric heater because it has high resistance, allowing it to generate heat efficiently. It also has a high melting point, ensuring that it does not melt or degrade under high temperatures. Additionally, it can resist a current of approximately 5 amperes, making it suitable for use in electric heaters. Therefore, all of the given reasons explain why nichrome wire is used in an electric heater.
17.
The force that tends to make a nucleus fly apart?
Correct Answer
B. Electrostatic repulsion
Explanation
Electrostatic repulsion refers to the force between two like charges that causes them to repel each other. In the context of a nucleus, it consists of positively charged protons being repelled by each other due to their electrostatic interactions. This repulsive force counteracts the strong nuclear force that holds the nucleus together, and if it becomes stronger than the nuclear force, it can cause the nucleus to break apart or fly apart. Therefore, electrostatic repulsion is the force that tends to make a nucleus fly apart.
18.
Inertia is a vector quantity. It has both magnitude and direction.
Correct Answer
B. False
Explanation
Inertia is not a vector quantity. It is a scalar quantity, meaning it only has magnitude and no direction. Inertia is the tendency of an object to resist changes in its state of motion or rest. It does not have a specific direction associated with it, as it is dependent on the mass of the object. Therefore, the statement that inertia is a vector quantity is false.
19.
In air, a baseball and a tennis ball would have the same terminal velocity.
Correct Answer
B. False
Explanation
The terminal velocity of an object is the maximum velocity it can reach when falling through a fluid, such as air. The terminal velocity depends on the object's mass, shape, and surface area. Since a baseball and a tennis ball have different masses and sizes, they will experience different amounts of air resistance, resulting in different terminal velocities. Therefore, the statement that a baseball and a tennis ball would have the same terminal velocity in air is false.
20.
In a vacuum, a bowling ball and a ping pong ball would accelerate at the same rate when dropped.
Correct Answer
A. True
Explanation
In a vacuum, both the bowling ball and the ping pong ball would experience the same acceleration when dropped. This is because the acceleration due to gravity is independent of the mass of the object. In other words, the force of gravity acting on both balls would be the same, causing them to accelerate at the same rate. The difference in their masses would only affect the force required to stop or change their motion, but not their acceleration in a vacuum.
21.
The acceleration of an object is inversely proportional to the net force applied to the object.
Correct Answer
B. False
Explanation
The statement is false because the acceleration of an object is directly proportional to the net force applied to the object, not inversely proportional. According to Newton's second law of motion, the net force acting on an object is equal to the mass of the object multiplied by its acceleration. Therefore, an increase in net force will result in an increase in acceleration, and vice versa.
22.
All terminal velocity, all motion stops.
Correct Answer
B. False
Explanation
This statement is false. Terminal velocity refers to the constant speed that an object reaches when the force of gravity pulling it downwards is balanced by the drag force pushing against it. When an object reaches terminal velocity, it continues to move at a constant speed, but it does not mean that all motion stops. The object will still be in motion, just at a constant speed without any acceleration.
23.
Three skydivers tied together fall faster than a single skydiver.
Correct Answer
B. False
Explanation
Three skydivers tied together do not fall faster than a single skydiver. In fact, the opposite is true. When skydivers are tied together, they experience increased air resistance due to their larger surface area. This increased air resistance slows down their fall, resulting in a slower descent compared to a single skydiver. Therefore, the statement is false.
24.
You can put a geosynchronous satellite in orbit directly over still water.
Correct Answer
B. False
Explanation
A geosynchronous satellite needs to be placed in orbit directly over the equator, not over still water. This is because the satellite's orbit must match the rotation of the Earth, and the equator is the only location where the satellite can remain stationary relative to the ground. Placing it over still water would not ensure that it stays in sync with the Earth's rotation. Therefore, the statement is false.
25.
In the periodic table, elements arranged in the same vertical column have different chemical properties.
Correct Answer
B. False
Explanation
Elements arranged in the same vertical column of the periodic table are known as groups or families. Elements within the same group have similar chemical properties due to the fact that they have the same number of valence electrons. These valence electrons determine the chemical behavior of an element. Therefore, elements in the same vertical column have similar chemical properties, not different ones. Hence, the given statement is false.