An electric circuit consists of a variable resistor
connected to a source of constant potential
difference. if the resistance of the resistor is
doubled, the current through the resistor is
(1) halved (3) quartered
(2) doubled (4) quadrupled

Describe the path of a ray that approaches a mirror parallel to the principal axis.

1. how to locate the image in converging(concave) mirror and diverging (convex) mirror with salt. 2. how to locate the image in a converging (convex) lens and diverging (concave) lens with salt.

Assume you measured the mass of the cart to be (500 ± 1) g and the mass of the additional mass you put on the cart to be (500 ± 1) g as well. since the scale you are using in the lab cannot measure objects heavier than 600g you will have to sum up individual pieces and propagate the error. so what would be the mass and the standard error of the cart and the mass