An electromagnet is a device that uses an electric current to produce a magnetic field. Electromagnets are typically composed of a piece of metal wrapped with wire and connected to a battery. The battery provides the electric current, and the loops or coils of wire enhance the magnetic field. The more loops there are, the stronger the magnetic field.

When electric current flows through the electromagnet, the metal core becomes magnetized, so it possesses a north pole and a south pole.

Motors place electromagnets inside of permanent magnets as shown below.

However, motors are designed so that the polarity of the electromagnet constantly flips. That is, the north pole becomes the south pole, and the south pole becomes the north pole, every time the electromagnet turns 180 degrees.

Why is it designed this way?
A.
to conserve the energy in the battery
B.
to constantly polarize the field magnet
C.
so the electromagnet will continuously turn
D.
so the magnetic field will get stronger

answer: the correct answer is 1.

explanation: there are various process in which a radioactive nuclei decays:

1) alpha decay: in this process, a heavier nuclei decays into lighter nuclei by releasing alpha particle. the mass number is reduced by 4 units.

2) electron capture: in this decay process, a parent nuclei absorbs an electron and gets converted into a neutron. simply, a proton and an electron combines together to form a neutron. mass number does not change in this process.

3) gamma ray emission: it is a decay process in which an unstable nuclei gives excess energy by a spontaneous electromagnetic process. this decay releases . this process does not change the mass number.

4) positron emission: it is a type of decay process, in which a proton gets converted to neutron and an electron neutrino. this is also known as -decay. in this the mass number remains same.

from the above information, we see that only alpha-decay is producing a change in the mass number of the nucleus.

the simple machine has three main features. they are:

fulcrum is the center point or pivot point of the machine. effort is input force/ applied force. load is external force/ output.

the keisha 's machine labels are

x : load

y: fulcrum

z: lever

massxgravity x heght=weightxheight= pe

4900=490xh

h=10