In a probe that uses the Hall effect to measure magnetic fields, a 13.4 A current passes through a 1.72 cm -wide 1.12 mm -thick strip of sodium metal. If the Hall emf is 1.72 μV , what is the magnitude of the magnetic field (take it perpendicular to the flat face of the strip)? Assume one free electron per atom of Na, and take its specific gravity to be 0.971

Which statement correctly describes the current in a circuit that is made up of any two resistors connected in parallel with a battery? a. the current in the battery and in each resistor is the same b. the current the battery equals to the sum of the currents in the resistors c.the current in the battery is less than the current in either resistor d. the current in the battery equals to the product of the currents in the resistors

Which of the following is the main energy source for the sun? a. fission of hydrogen b. fusion of hydrogen c. fusion of helium d. fission of iron

Iron is a transition metal with multiple oxidation numbers. (answer the following) a. what is the iron (ii) ion? how does it differ from the iron (iii) ion? b. if iron were to bond with oxygen, predict the formula for each oxidation number of iron. c. how would each formula be named?