Physics Mock Test- 5 - Class 10 MCQ

When light enters the eye, most of the refraction takes place at the outer surface of the cornea. The crystalline lens only makes some finer adjustment.

Cilliary muscles modify the curvature of eye lens. When eye muscles are relaxed, eye lens becomes thinner thereby are relaxed, eye lens becomes thinner thereby increase in the focal length of eye lens.

• Concave Lens: A concave lens is a diverging lens that is thinner at the center than at the edges.


• Focal Length: The focal length of a lens is the distance between the lens and the point where light rays parallel to the optical axis converge or appear to diverge after passing through the lens.


• Sign Convention: In the sign convention for lenses, the focal length of a concave lens is considered negative.


• Image Formation: When a concave lens forms a real image, the focal length is negative.


• Real Image: A real image is formed when light rays actually converge at a point to form an image that can be projected onto a screen.


• Virtual Image: A virtual image is formed when light rays appear to diverge from a point but do not actually converge to form a real image.


• Conclusion: The focal length of a concave lens is always negative, regardless of whether a real or virtual image is formed.

The order of decreasing accuracy in measurement of focal length of a convex lens by the given techniques is DBCA.

D - Student D used a well-illuminated distant tree as the object and a white thick board held on a stand as the screen. This technique is more accurate because the object is a distant tree, which provides a nearly parallel beam of light, and the screen is held on a stand.

B - Student B used a distant tree in the absence of sunlight as the object, and a white thick board held on a stand as the screen. This technique is also quite accurate as the object is a distant tree, which provides a nearly parallel beam of light, and the screen is held on a stand.

C - Student C used a well-illuminated laboratory window grill as the object and a white paper sheet held on a stand as the screen. This technique is less accurate than Student B's technique because the object is a window grill, which may not provide a sufficiently distant or parallel beam of light, but the screen is held on a stand.

A - Student A used the window grill in the laboratory as the object and a white paper sheet held in hand as the screen. This technique is the least accurate because the object is the window grill in the laboratory, which may not provide a sufficiently distant or parallel beam of light, and the screen is held in hand, leading to potential movements and vibrations that could affect the measurement.

Cell is the device which is used to maintain the potential difference between two points of the conductor.

An electric circuit is the representation of the whole path of current and also the various devices connected in it, like Cell, Resistor, etc.

• Michael Faraday: The discovery of electromagnetic induction is credited to Michael Faraday, a British scientist.


• Experiment: Faraday's famous experiment involved moving a magnet in and out of a coil of wire. He observed that this motion induced a current in the wire.


• Principle: This phenomenon became known as electromagnetic induction, where a changing magnetic field induces an electromotive force (EMF) in a conductor.


• Faraday's Law: Faraday formulated Faraday's law of electromagnetic induction, which states that the EMF induced is proportional to the rate of change of magnetic flux through the coil.


• Significance: Faraday's discovery of electromagnetic induction laid the foundation for the development of electric generators and transformers, revolutionizing the field of electricity.

Irrespective of the position of an object both convex mirror and plane mirror form virtual and erect images. Of course image formed by a plane mirror is of same size as the object but image formed by convex mirror is always diminished one.

The laws of reflection hold good for light reflected from any smooth surface irrespective of their shapes.

H = Pt

• Prevent electric shocks: When an electrical appliance is not properly earthed, there is a risk of electric shocks if there is a fault in the appliance or the wiring. Earthing helps to safely divert any excess electrical current to the ground, preventing shocks to users.



• Protect against electrical fires: Proper earthing also reduces the risk of electrical fires by providing a path for excess current to safely dissipate. This helps to prevent overheating and potential fire hazards.



• Ensure electrical safety: By grounding high powered electrical appliances, it ensures the safety of both the users and the appliance itself. It is an essential safety measure to prevent accidents and injuries related to electricity.



• Compliance with regulations: In many countries, it is a legal requirement for high powered electrical appliances to be properly earthed to meet safety standards and regulations. Failure to comply can result in fines and penalties.



• Protect electronic equipment: Proper earthing also helps to protect sensitive electronic equipment from damage caused by power surges and fluctuations. It provides a stable reference point for the electrical system, ensuring the proper functioning of the appliances.

The bigger hole is connected to the earth wire and the other two holes are connected to the live wire and neutral wire respectively.

• Overloading: Overloading occurs when too many devices are connected to a circuit, drawing more current than the circuit can handle.


• Increased Current: When a circuit is overloaded, the current flowing through the circuit increases.


• Effect on Circuit: The increased current can lead to overheating of components, voltage drops, and potential damage to the circuit.


• Result: Therefore, in the case of overloading, the current in the circuit becomes more than the normal operating current.

Voltage (V) = 270 Volts

Current (I) = 0.5 A

Power (P) = V x I
= 270 x 0.5 = 135 watt

P = I² R = (10)² × 5 = 500 watt = 0.5 kW

t = 30 minute = 0.5 hr

E = P × t = 0.5 kW × 0.5 hr = 0.25 kWh

Violet and blue colour have shorter wavelength.
So, they scattered more than lights of other colour by the molecules present in the atmosphere.

To focus the objects, situated at different distances from the eye, distinctly at the retina the eye lens adjusts its focal length. This adjustment of focal length of eye lens is achieved by the contraction/relaxation of the ciliaiy muscles.

Overloading occurs when there is any fault in the appliances or the insulation of wire got damaged. It also occurs when there is sudden hike in supply voltage.

In Fleming’s left-hand rule the thumb indicates the direction of mechanical force acting on the conductor. The forefinger points in the direction of magnetic field and the central finger in the direction of current flowing in the conductor.

Fuse wire must have high conductivity, low melting point and it do not burn due to oxidation. These characteristics of a fuse wire make it possible to prevent from damages.

Hypermetropia can be corrected by using a convex lens. A convex lens converges the incoming light such that the image is formed on the retina.

In myopia, u = infinity , v = d = distance of far point
By 1/F = 1/v - 1/u
We get  f = -d
Since the f is negative, the lens used is concave.

The near point of the eye is the minimum distance of the object from the eye, which can be seen distinctly without strain. For a normal human eye, this distance is 25 cm. The far point of the eye is the maximum distance to which the eye can see the objects clearly. The far point of the normal human eye is infinity.