Physics Tutors in Chand Nagar, Delhi

The ability of a lens to bend the light rays is called power of lens. A lens of shorter focal length bends the light ray more, and have greater power.

Thus power of a lens is defined as the reciprocal of its focal length (f) in metres.

 SI unit of power is ‘Dioptre’ denoted by letter D

​ The power of a convex lens a positive and that of a concave lens is negative. Power of lens P=1/f(in meters)

Power of lens P=100/f(in centi meters)

ANSWER B

Caterpillar tracks work on the same principle of a conveyer belt. This belts enable the tanks to spread their weight over a larger surface area and thus exert a lower force per unit area on the ground. The large surface area of the tracks distributes the weight of the vehicle better than rubber tyres on an equivalent vehicle, enabling continuous tracked vehicles to traverse soft ground with less likelihood of becoming stuck due to sinking

Sunlight is the main source of UV radiation, even though UV rays make up only a small portion of the sun's rays.

Sunlight is not the only source of UV radiation on earth. Other sources includes

1.            Tanning booths

2.            Mercury vapor lighting (often found in stadiums and school gyms)

3.            Some halogen, fluorescent, and incandescent lights

4.            Some types of lasers

UV radiation is divided into 3 main groups:

UVA

UVA rays have the least energy among UV rays. These rays can cause skin cells to age and can cause some indirect damage to cells’ DNA. UVA rays are mainly linked to long-term skin damage such as wrinkles, but they are also thought to play a role in some skin cancers.

UVB

UVB rays have slightly more energy than UVA rays. They can damage the DNA in skin cells directly, and are the main rays that cause sunburns. They are also thought to cause most skin cancers.

UVC

UVC rays have more energy than the other types of UV rays. Fortunately, because of this, they react with ozone high in our atmosphere and don’t reach the ground, so they are not normally a risk factor for skin cancer. But UVC rays can also come from some man-made sources, such as arc welding torches, mercury lamps, and UV sanitizing bulbs used to kill bacteria and other germs (such as in water, air, food, or on surfaces).

A cyclotron is a type of particle accelerator invented by Ernest O. Lawrence in 1929–1930. It can accelerate charged particles along a spiral path. Lawrence was awarded the 1939 Nobel Prize in physics for this invention

Cyclotron works on a principle that a charged particle moving perpendicular to magnetic field experiences a magnetic force (Lorentz).  This force makes the particle accelerate.

Construction: It consists of a hollow metal cylinder that is divided into two sections D1 and D2.  These sections are called Dees.  They are enclosed in an evacuated chamber.  The Dees are kept separated from each other and a source of ions is placed at the centre.  They are placed between the two poles of a strong electromagnet.  The Dees are connected to a high-frequency oscillator.

Cyclotron involves the use of an electric field that is used to accelerate charged particles across the gap between two D shaped magnetic field regions.  The magnetic field applied is perpendicular to the paths of the charged particles. When a positive ion with a charge ‘q’ and mass ‘m’ is ejected from the source and is accelerated towards the Dee having a negative potential.  Since the magnetic field is perpendicular to the movement of ion, it experience magnetic Lorentz force and starts to moves in a circular path.  When the ion arrives at the gap between the Dees the polarity gets reversed.  Thus the particle once again and moves into the other Dee gaining a higher velocity.  The particle now moves in a spiral path that has an increased radius.  When it comes near the edge it can be taken out with the help of deflector plate.  The particle now having high energy is now allowed to hit the target.

Electric current is the flow of electrons in a wire. Insulating materials doesn’t have free electrons in their valence shells.  In conductor metals, the outer electrons of the atoms belong to a ‘cloud’ of delocalised electrons. They are no longer firmly held by a specific atom, but instead they can move freely through the lattice of positive metal ions. Normally they move randomly. However, when a potential difference is applied, they are pushed away from the negative terminal and drawn to the positive one creates a flow of current in the opposite direction

Electric current is the flow of electrons in a wire. Insulating materials doesn’t have free electrons in their valence shells.  In conductor metals, the outer electrons of the atoms belong to a ‘cloud’ of delocalised electrons. They are no longer firmly held by a specific atom, but instead they can move freely through the lattice of positive metal ions. Normally they move randomly. However, when a potential difference is applied, they are pushed away from the negative terminal and drawn to the positive one creates a flow of current in the opposite direction ie, from positive side to negative side

Both type of majority carriers

'' Time period of given SHM is 3 sec. 3 sec in the scence 2*pi/(2*pi/3). So time taken to reach from mean to extreme is one fourth of time period. So 3/4 sec will be taken.

If you are talking about stopping potential then it must increase because to stop high energy electrons we have to apply high opposing potential.

measured by odometer