behind the mirror
Contrary to real images, virtual images cannot be illustrated on a screen. The optical image will appear at the point of divergence ( of outgoing rays from a point). It is an optical image that seems to be projected from behind the mirror.
Answer:
The electron affinity of an atom or molecule is defined as the amount of energy released when an electron is attached to a neutral atom or molecule in the gaseous state to form a negative ion.
<u>Answer;</u>
<em>D. The object’s weight changes, but its mass stays the same.</em>
<u>Explanation;</u>
- Mass is the amount of matter in a object, which is measured in kilograms. Mass of an object is measured using a beam balance. It is important to note that the mass of an object or a body remains constant, and does not vary from one place to another. For instance the mass of a person on the moon will be the same as when the person is on the earth surface.
- Weight on the other hand is the measurement of gravitational pull of an object. weight is measured using a spring balance and measured in Newtons. Weight varies from one place to another depending on the gravitational pull of a given surface.
<u>The statements that describes energy best as follows:
</u>
- The total amount of energy in the universe remains constant.
- Energy can be converted from one form to another.
- Energy cannot be created or destroyed.
<u>Explanation
:</u>
The Universe is a closed system of energy from where the thermodynamics first law is quoted i.e. the energy in the closed system remains constant.
The energy in the closed system can neither be created nor destroyed in the absence of external energy supply. However, it keeps on changing from one state to another. These are the absolute statements about the total energy existing in the Universe.
There are many energy forms existing in the Universe such heat, mass, vibrations etc. that consistently change their form from one to another but the total energy amount is always constant until external energy is applied to the system.
According to the quantum theory, even an electron absorbs or emits energy while jumping from one energy band to the other. There is never a case where energy can create or destroy in a closed system.
Answer:
Angle = 0.2520 radians
Explanation:
Complete question:
Sound with frequency 1220Hz leaves a room through a doorway with a width of 1.13m . At what minimum angle relative to the centerline perpendicular to the doorway will someone outside the room hear no sound? Use 344m/s for the speed of sound in air and assume that the source and listener are both far enough from the doorway for Fraunhofer diffraction to apply. You can ignore effects of reflections.
Given Data:
Speed of sound =v= 344 m/sec ;
Width of doorway =d= 1.13m ;
Frequency of sound =f= 1220 Hz ;
Solution:
As we know that
Wvelength = w = v/f = 344/1220 = 0.281967m
Now we also know that
w = dsin(A) where A is the angle
A = arcsin(w/d) =14.44° = 14.44*(3.14/180) = 0.2520 radians
At the angle of 0.252 radians relative to the centreline perpendicular to the doorway a person outside the room will hear no sound under given conditions.
