How do i identify the symbols used for positive and negative charge

State one advantage and one disadvantage of using a plane mirrior as a driving mirrior

What is the role of the ocular lens?

Two technicians are discussing a resistance measurement between the can-h and can-l wires. technician a says this measurement should be done with the ignition switch in the "run" position. technician b states that a measurement of 0 ohms indicates an open in the network. which technician is correct?