Actually Welcome to the Concept of the Optical Devices.
Now basically here the devices that can spread light over apart are the CONCAVE LENS and Convex mirror.
so the Answer is
C. B and D
Check the power source. Your thermostat may just not be connected right or at all. A blown fuse, tripped circuit breaker or dead batteries will prevent the thermostat from turning on your furnace.
Dirty thermostat? That’ll cause issues. Clean up any dust, dirt, spider webs and other debris. Any of these things can coat the inside of the thermostat and interfere with both electrical and mechanical functions of the thermostat. Put this on your get-ready-for-winter cleaning list. Just use a soft, clean brush to clean the inside components gently. Don’t get anything wet. Also you can use a can of compressed air, such as is used for electronics, to clear debris.
Check for any loose wires or terminal screws inside the thermostat. Make sure wires aren’t corroded or detached. Never remove the thermostat cover without removing the batteries or turning off the power at the fuse or breaker box. Tighten screws and secure loose wires if needed.
It may be time to replace your thermostat is it’s old. They aren’t meant to last forever and an old thermostat may be costing you a lot of money in wasted energy and time spent tinkering with an outdated model. There are great programmable thermostats available now that are easy to use and simple to connect to your existing HVAC system. Click here for more info on programmable thermostats.
1. neutral particles (neutrons) are in the nucleus
2. nucleus is in the nucleus
3. electron cloud is in the electron cloud
4. positively charged particles (protons) are in the nucleus
5. negatively charged particles (electrons) are in the electron cloud
Explanation :
The full form of laser is Light Amplification by Stimulated Emission of Radiation. It has particles of very high energy. It points in one direction.
Greg is giving a slide show presentation to a large audience. It is very important to make the presentation informative. By using a laser, we can focus on the important part of the presentation. So that we can highlight the important points.
(a) As the car is moving with constant velocity, it means the rate change of velocity does not change, therefore the average acceleration of the car is zero.
Thus, there is no acceleration, when velocity is constant.
(b) Average acceleration,
Here, v is final velocity and u is the initial velocity and 
is the time interval.
As twelve seconds later, the car is halfway around the track and traveling in the opposite direction with the same speed, therefore
Thus, the average acceleration of the car is 
in the direction to the left.
