<span>In order for the results to be valid, the dependent variable can only be affected by the independent variable, so somethings need to be kept constant. The things that need to be kept constant are called controlled variables.</span>
Electricity.
When electricity flows through wire (such as a battery circuit) it creates a magnetic field around the wire.
Explanation:
spectral lines or signatures of elements depend on temperature, the temperature of the sun is about 5800 K.
at this temperature most calcium atoms are excited to higher energy states than hydrogen atoms and this means that calcium atoms are gonna have more signatures than the atoms of hydrogen.
the statement that the sun shows weak hyrogen lines and strong calcium line is wrong because at the sun's temperature most of the hydrogen atoms are in lower energy states while calcium atoms are in higher energy states hence calcium has more or ''strong'' lines than hydrogen.
If the boat is i travling at 10 m/s and the river is 8.0 m/s the boats speed is 18.0 m/s
