Speed of wave = frequency x wavelength
= 250 x 6 = 1500 m/s.
On the whole, the metals burn in oxygen to form a simple metal oxide. Beryllium is reluctant to burn unless it is in the form of dust or powder. Beryllium has a very strong (but very thin) layer of beryllium oxide on its surface, and this prevents any new oxygen getting at the underlying beryllium to react with it.
<span>Voltage overcomes the resistance of the electromagnet winding to force a current through that resistance. The field strength is proportional to the coil current. More voltage pushes more current. More voltage builds up the current faster, as well as forcing it to a higher final value. </span>
A concussion, which is a form of mild traumatic brain injury, occurs after a blow to the head. The brain is surrounded by fluid and protective membranes called meninges, which usually cushion the brain. During an impact, the brain is pushed against the inside of the skull and can be bruised.
