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Light is a transverse, electromagnetic wave that can be seen by the typical human. The wave
nature of light was first illustrated through experiments on diffraction and interference. Like all
electromagnetic waves, light can travel through a vacuum.
Light is composed of electromagnetic waves that can travel without a medium, unlike sound. ...
A wavelength (which varies inversely with frequency ) manifests itself as color, while wave
amplitude is perceived as luminous intensity or brightness; it is measured by the standard unit of
a candela.
There are three modes of heat transfer: conduction, convection, and radiation. Any energy
exchange between bodies occurs through one of these modes or a combination of them.
Conduction is the transfer of heat through solids or stationery fluids.
Earthing means connecting the dead part (it means the part which does not carries current under
normal condition) to the earth for example electrical equipment’s frames, enclosures, supports
The purpose of earthing is to minimize risk of receiving an electric shock if touching metal parts
when a fault is present. Generally green wire is used for this as a nomenclature.
Under fault conditions the non-current carrying metal parts of an electrical installation such as
frames, enclosures, supports, fencing etc. may attain high potential with respect to ground so that
any person or stray animal touching these or approaching these will be subjected to potential
difference which may result in the flow of a current through the body of the person or the animal
of such a value as may prove fatal.
To avoid this non-current carrying metal parts of the electrical system are connected to the
general mass of earth by means of an earthing system comprising of earth conductors to conduct
the fault currents safely to the ground.
Earthing has been accomplished through bonding of a metallic system to earth. It is normally
achieved by inserting ground rods or other electrodes deep inside earth.
Earthing is to ensure safety or Protection of electrical equipment and Human by discharging the
electrical energy to the earth.
Grounding means connecting the live part (it means the part which carries current under normal
condition) to the earth for example neutral of power transformer.
Grounding is done for the protections of power system equipment and to provide an effective
return path from the machine to the power source. For example grounding of neutral point of a
star connected transformer.
Grounding refers the current carrying part of the system such as neutral (of the transformer or
Because of lightening, line surges or unintentional contact with other high voltage lines,
dangerously high voltages can develop in the electrical distribution system wires. Grounding
provides a safe, alternate path around the electrical system of your house thus minimizing
damage from such occurrences.
Generally Black wire is used for this as a nomenclature.
All electrical/electronic circuits (AC & DC) need a reference potential (zero volts) which is
called ground in order to make possible the current flow from generator to load. Ground is May
or May not be earthed. In Electrical Power distribution it is either earthed at distribution Point or
at Consumer end but it is not earthed in Automobile( for instance all vehicles’ electrical circuits
have ground connected to the chassis and metallic body that are insulated from earth through
tires). There may exist a neutral to ground voltage due to voltage drop in the wiring, thus neutral
does not necessarily have to be at ground potential.
In a properly balanced system, the phase currents balance each other, so that the total neutral
current is also zero. For individual systems, this is not completely possible, but we strive to come
close in aggregate. This balancing allows maximum efficiency of the distribution transformer’s
secondary winding
Micro Difference between earthing & Grounding:
There is no major difference between earthing and Grounding, both means “Connecting an
electrical circuit or device to the Earth”. This serves various purposes like to drain away
unwanted currents, to provide a reference voltage for circuits needing one, to lead lightning away
from delicate equipment. Even though there is a micro difference between grounding & earthing.
(1) Difference in Terminology:
In USA term Grounding is used but in UK term Earthing is used.
Earthing and Grounding both is refer to zero potential but the system connected to zero potential
is differ than Equipment connected to zero potential .If a neutral point of a generator or
transformer is connected to zero potential then it is known as grounding. At the same time if the
body of the transformer or generator is connected to zero potential then it is known as earthing.
The term “Earthing means that the circuit is physically connected to the ground and it is Zero
Volt Potential to the Ground (Earth) but in case of “Grounding” the circuit is not physically
connected to ground, but its potential is zero(where the currents are algebraically zero) with
respect to other point, which is also known as “Virtual Grounding.”
Earth having zero potential whereas neutral may have some potential. That means neutral does
not always have zero potential with respect to ground. In earthing we have Zero Volt potential
references to the earth while in grounding we have local Zero Volt potential reference to circuit.
When we connect two different Power circuits in power distribution system, we want to have the
same Zero Volt reference so we connect them and grounds together. This common reference
might be different from the earth potential.
Edit1: Both grounding and earthing are synonymous. The difference is the width of Atlantic.
British terminology calls it earthing whereas the American terminology refers to it as grounding.
Earthing means connecting the dead part (it means the part which does not carries current under
normal condition) to the earth. For example electrical equipment’s frames, enclosures, supports
While grounding means connecting the live part (it means the part which carries current under
normal condition) to the earth. For example neutral of power transformer.
The purpose of earthing is to minimize risk of receiving an electric shock if touching metal parts
when a fault is present.
While the purpose of grounding is the protections of power system equipment and to provide an
effective return path from the machine to the power source. For example grounding of neutral
point of a star connected transformer.
Ground is a source for unwanted currents and also as a return path for main current some times.
While earthing is done not for return path but only for protection of delicate equipments.
Mental health is a level of psychological well-being or an absence of mental illness - the
"psychological state of someone who is functioning at a satisfactory level of emotional and
behavioural adjustment".
Assessments may be done for a number of reasons. It can assist other professionals such as
developmental pediatricians, doctors, and/or therapists in arriving at a more accurate and
comprehensive diagnosis of the patient. It can help schools and teachers understand their
students better and resultantly, come up with better and more creative learning strategies. It can
help parents and family members understand what is happening to the affected person and how
they can work together to find solutions. It can help individuals understand themselves.
What is mental illness? A mental illness is a disease that causes mild to severe disturbances in
thought and/or behavior, resulting in an inability to cope with life’s ordinary demands and
routines. There are more than 200 classified forms of mental illness. Some of the more common
disorders are depression, bipolar disorder, dementia, schizophrenia and anxiety disorders.
Symptoms may include changes in mood, personality, personal habits and/or social withdrawal.
Mental health problems may be related to excessive stress due to a particular situation or series
of events. As with cancer, diabetes and heart disease, mental illnesses are often physical as well
as emotional and psychological. Mental illnesses may be caused by a reaction to environmental
stresses, genetic factors, biochemical imbalances, or a combination of these. With proper care
and treatment many individuals learn to cope or recover from a mental illness or emotional
Warning Signs and Symptoms To learn more about symptoms that are specific to a particular
mental illness, search under Mental Health Information or refer to the Mental Health America
brochure on that illness. The following are signs that your loved one may want to speak to a
medical or mental health professional. It is especially important to pay attention to sudden
changes in thoughts and behaviors. Also keep in mind that the onset of several of the symptoms
below, and not just any one change, indicates a problem that should be assessed. The symptoms
below should not be due to recent substance use or another medical condition.
In Adults, Young Adults and Adolescents: Confused thinking Prolonged depression (sadness or
irritability) Feelings of extreme highs and lows Excessive fears, worries and anxieties Social
withdrawal Dramatic changes in eating or sleeping habits Strong feelings of anger Strange
thoughts (delusions) Seeing or hearing things that aren't there (hallucinations) Growing inability
to cope with daily problems and activities Suicidal thoughts Numerous unexplained physical
ailments Substance use In Older Children and Pre-Adolescents: Substance use Inability to cope
with problems and daily activities Changes in sleeping and/or eating habits Excessive complaints
of physical ailments Changes in ability to manage responsibilities - at home and/or at school
Defiance of authority, truancy, theft, and/or vandalism Intense fear Prolonged negative mood,
often accompanied by poor appetite or thoughts of death Frequent outbursts of anger In Younger
Children: Changes in school performance Poor grades despite strong efforts Changes in sleeping
and/or eating habits Excessive worry or anxiety (i.e. refusing to go to bed or school)
Hyperactivity Persistent nightmares Persistent disobedience or aggression Frequent temper
tantrums How to cope day-to-day Accept your feelings Despite the different symptoms and types
of mental illnesses, many families who have a loved one with mental illness, share similar
experiences. You may find yourself denying the warning signs, worrying what other people will
think because of the stigma, or wondering what caused your loved one to become ill. Accept that
these feelings are normal and common among families going through similar situations. Find out
all you can about your loved one’s illness by reading and talking with mental health
professionals. Share what you have learned with others. Handling unusual behavior The outward
signs of a mental illness are often behavioral. A person may be extremely quiet or withdrawn.
Conversely, he or she may burst into tears, have great anxiety or have outbursts of anger. Even
after treatment has started, some individuals with a mental illness can exhibit anti-social
behaviors. When in public, these behaviors can be disruptive and difficult to accept. The next
time you and your family member visit your doctor or mental health professional, discuss these
behaviors and develop a strategy for coping. Your family member's behavior may be as
dismaying to them as it is to you. Ask questions, listen with an open mind and be there to support
them. Establishing a support network Whenever possible, seek support from friends and family
members. If you feel you cannot discuss your situation with friends or other family members,
find a self-help or support group. These groups provide an opportunity for you to talk to other
people who are experiencing the same type of problems. They can listen and offer valuable
advice. Seeking counseling Therapy can be beneficial for both the individual with mental illness
and other family members. A mental health professional can suggest ways to cope and better
understand your loved one’s illness. When looking for a therapist, be patient and talk to a few
professionals so you can choose the person that is right for you and your family. It may take time
until you are comfortable, but in the long run you will be glad you sought help. Taking time out
It is common for the person with the mental illness to become the focus of family life. When this
happens, other members of the family may feel ignored or resentful. Some may find it difficult to
pursue their own interests. If you are the caregiver, you need some time for yourself. Schedule
time away to preventbecoming frustrated or angry. If you schedule time for yourself it will help
you to keep things in perspective and you may have more patience and compassion for coping or
helping your loved one. Being physically and emotionally healthy helps you to help others.
“Many families who have a loved one with mental illness share similar experiences” It is
important to remember that there is hope for recovery and that with treatment many people with
mental illness return to a productive and fulfilling life.