How does a photocopier use static electricity?
a. positively charged ink is attracted to negatively charged paper
b. positively charged ions power the machine
c. negatively charged toner is attracted to a positively charged image
d. negatively charged ink is repelled from the original onto the copy plate

ANSWER:

a. Positively charged ink is attracted to negatively charged paper

EXPLANATION:

Inside a copier there is a special drum you just charge it with static electricity. There is also a black powder known as toner. The drum attracts the toner particles. A beam of light moves across the paper that you have placed on the copying machine's glass surface. Light reflects from white areas of the paper and hits the drum below. Dark areas do not reflect light onto the drum, leaving behind areas of positively charged particles on the drum's surface. Negatively charged, toner is then spread over the surface of the drum. A positively charged sheet of paper then passes over the surface of the drum, attracting the particles of toner. The paper is then heated and pressed to print the image.

white blood cells or wbc s are mainly 2 types-

1.agranulocytes

2.granulocytes

the monocytes or macrophages of agranulocytes , dendritic cells which are accessory leucocytes, and b cells which is one type of lymphocytes   identify the antigens present on the pathogen's surface. these three cells are called antigen presenting cells(apc) which are phagocytes and destroy the antigens by secreting antitoxins. besides this leukocyte is always plays vital role in the immunity of the body.

regents of the university of california v. bakke, 438 u.s. 265 (1978), was a landmark decision by the supreme court of the united states. it upheld affirmative action, allowing race to be one of several factors in college admission policy.