Preformed vitamin A occurs naturally in dairy products, eggs, fish and meat, especially liver. Carotenoids are found in bright yellow and orange vegetables such as carrots, pumpkin and sweet potatoes, broccoli and spinach.he best food sources are beef and chicken liver, whole milk, cheese, and eggs. You get vitamin A from beta-carotene in carrots, mango, sweet potato, spinach, cantaloupe, kale, apricots, red pepper, broccoli, and fortified foods.
When the switch is first closed, the voltage across the capacitor (which we were told was fully discharged) is zero volts; thus, it first behaves as though it were a short-circuit. Over time, the capacitor voltage will rise to equal battery voltage, ending in a condition where the capacitor behaves as an open-circuit.
Capacitors are components that are used to store an electrical charge and are used in timer circuits. A capacitor may be used with a resistor to produce a timer. Sometimes capacitors are used to smooth a current in a circuit as they can prevent false triggering of other components such as relays. When power is supplied to a circuit that includes a capacitor-the capacitor charges up. When power is turned off the capacitor discharges its electrical charge slowly.